Left or right handed? The confusion begins...

I found this on casebook, deeply analysing the case of Jack the Ripper’s preferred hand. Yes, it's long... but interesting...

From the time of the Ripper killings until right up to the present day, it has often been suggested the Jack the Ripper was left-handed. As a left-handed myself, this intrigued me: was Jack the Ripper one of my own? Or was the suggestion that the Ripper was left-handed more of a product of the negative connotations attached to left-handed people, and to the left hand in general, than any hard forensic evidence that the knife wounds and bruising were inflicted by a sinistral killer?
At first the second of these possibilities might seem unlikely, for the suggestion the Ripper was left-handed came from the very best of sources: Dr Rees Ralph Llewellyn, the doctor who carried out the post mortem on Polly Nichols. Dr Llewellyn's findings were summarised by Inspector John Spratling thus:
(...) her throat had been cut from left to right, two distinct cuts being on the left side, the windpipe, gullet and spinal cord being cut through; a bruise apparently of a thumb being on the right lower jaw, also one on the left cheek, the abdomen had been cut open from centre of bottom of ribs along right side, under pelvis to left of stomach, there the wound was jagged; the omentum, or coating of the stomach, was also cut in several places, and two small stabs on private parts; apparently done with a strong bladed knife; supposed to have been done by some left handed person; death being almost instantaneous.
What was it in these details that led Dr Llewellyn to suggest that the killer was left-handed?
Well, his assertion seems to be based on two things: the direction of the knife wounds and the location of the facial and throatal bruising. Llewellyn asserted that the knife wounds ran from left to right. Now this was the case with all the canonical victims, except possibly Kelly, who was so comprehensively carved up that it does not appear to have been noted which direction the neck wound (or wounds) ran in. Whether or not left to right knife wounds indicate sinistrality, however, depends on where the Ripper stood, bent or squatted as he inflicted the wounds.
If they were inflicted from behind a standing victim, a left-handed would inflict wounds which ran from right to left. Forensic analysis, however, shows that this would not have been how the wounds would have been inflicted. The Ripper's modus operandi was to first render his victims unconscious by strangling them. This is indicated by the fact that, in the case of Nichols, discolouration was noted on the face and that, in the case of Chapman, her tongue was swollen and protruding from her front teeth. The point, therefore, is that the knife wounds must have been inflicted with the victim lying on the ground. Conceivably, the killer could have inflicted the knife wounds by standing astride the body and bending over it. This would have resulted in left to right knife wounds from a right-handed killer, or right to left knife wounds from a left-handed killer. This position is unlikely, however: it is uncomfortable, it might result in the murderer becoming covered in blood (from the spurt coming from the severed carotid artery) and it would obscure what little light the murderer might have to work by. It would also lessen his chance of observing anyone approaching him.
The more likely scenarios are that the Ripper inflicted his knife wounds from the victim's side or from behind her head. A left-handed killer would squat by the victim's right side and inflict left to right wounds. Or he would squat by the left side of the victim's head, steadying the head with his right hand and inflicting the neck wounds with his left hand, producing a right to left cut. A right-handed killer would squat by the victim's left side and inflict right to left knife wounds, or to the right of the victim's head, steadying the head with his left hand and inflicting a left to right would with his right hand. My suspicion, however, is that the Ripper squatted at the top of his victim's head so as to face her feet. The reason for this is that the killer could in this way not only steady the victim's head with his non-preferred hand, while wielding the knife in his preferred hand, but direct the jet of blood from the carotid artery away from him. Gripping the face in this way would have been especially important if the victim were still conscious. I am not the first person to form this opinion: Phil Sugden reached it before me.
From this position, then, it would be a right-handed killer who would inflict left to right knife wounds, and a left-handed killer who would inflict right to left knife wounds. This analysis applies to all victims except Mary Kelly. She is a special case because the position of the bed, wedged against a corner wall, compelled the Ripper to work at her left side. (I suspect that the police photographer who took the photograph of Kelly from behind the bed would have had to pull the bed away from the wall in order to do so.)
The facial bruising observed by Dr Llewellyn also gives us a clue to the Ripper's handedness. He recorded that there were bruises on both sides of her face: one, apparently a thumb mark, on the right lower jaw, and another on the left cheek. Sugden suggests this indicates a right-handed attack from the top of Nichol's head, as outlined above. The Ripper would have gripped her head with his left hand, thus forming the bruise on her right lower jaw with his thumb and the bruise on her left cheek with his fingers. He then inflicted the knife wounds with his right hand.
Further indications of the Ripper's handedness can be gleaned from the abdominal mutilations. The most fruitful information on these is to be found in the Eddowes murder, for in, this case we have a great deal of information: there is not just Dr Brown's post mortem report, but full-length photographs and annotated drawings. At first glance, assuming the cut was inflicted downwards, it appears that the abdominal wound veered to the left, indicating a left-handed knife user. In fact, Dr Brown's evidence makes it quite clear that the wound was inflicted upwards from the abdomen towards the sternum. This means the wound veered right, right-handed knife usage. Again someone got here before me. The forensic expert Prof James Cameron examined both photographs and sketches and concluded that the Ripper was dextral: "The incision," he remarked, "drags to the right, as would happen, and is deeper as more viscera is exposed."
I have already said Kelly is a special case. We do not appear to have any record of which direction her neck wounds were inflicted in, but the circumstances dictated that the Ripper worked from her left aide. In her case, therefore, the neck wounds must have run from right to left. the blood spatterings on the wall (from the severed right carotid artery) back up this assertion, and there is a further clue which may point to the final, fatal neck wound being inflicted with the right hand. Dr Phillips, one of the doctors who carried out the examination of Kelly, observed that there was a large quantity of blood on the right side of the pillow and sheet and under the right-hand side of the bedstead. He therefore believed she had been killed while lying further back on the bed and then subsequently moved towards the killer so he could carry out the mutilations. The initial position of Kelly's throat - up towards the corner of the wall - would have made it awkward for the Ripper to inflict the neck wound left-handed: not impossible by any means, but left handedness would have been a distinct handicap in such a position. One further thought: in the main full-length photograph of Kelly, two areas of mutilations are clearly visible on her left arm. The one on her lower arm is especially revealing, for it's direction, whether inflicted before or after her hand was placed across the abdomen, is towards the right. In other words, it could only have been inflicted with the right hand, unless the killer inflicted it sinistrally in an unnatural and extremely awkward position, with his left elbow pointing up towards the ceiling - hardly something he would be likely to do.
All of this points to the inescapable conclusion that the Ripper was tight-handed. Indeed, Dr Llewellyn himself later came to doubt his initial conclusion. A note penned by Chief Inspector Donald Swanson, dated 19th October 1888, records the following: "At first the Doctor was of the opinion that the wounds were caused by a left-handed person but he is now doubtful." Macnaghten, in the Scotland Yard version of his 'Memoranda', also noted: "The theory that the Whitechapel murderer was left-handed, or, at any rate, ambi-dexter', had its origin in the remark made by a doctor who examined the corpse of one of the earliest victims; other doctors did not agree with him."
Why, then, did Dr Llewellyn initially believe that the killer was left-handed? One clue is to be found in the newspaper reports. Both The Times and The Telegraph reported in their issues of 1st September 1888 that Dr Llewellyn believed the Ripper might be left-handed. The Times continued: "He made a second examination of the body in the mortuary, and on that based his conclusion, but will make no actual post mortem until he receives the coroner's orders." Dr Llewellyn concluded that the Ripper might be left-handed before even carrying out a post modern! And when he did come to conduct the post mortem, he had already made up his mind. This bespeaks more of prejudice towards left-handers than the objective, reasoned conclusions of the pathologist.
But why plump for a left-handed killer? Christopher Frayling has shown how commentators on the Ripper case have had a tendency to blame the murders on minority groups. In the case of Dr Llewellyn. I would suggest that left-handers were the chosen minority. But why? What was the association in Dr Llewellyn's mind between murder and left- handedness? The answer is that there is an extremely long association in popular tradition between evil and the left ' hand. The Latin word for 'left' is 'sinister'. The Italian word for 'left' is 'mancini', which also means 'evil' or 'deceitful'. The Oxford English Dictionary defines 'left-handed' as in part meaning 'doubtful', 'questionable', 'ill-omened' and 'characterised by underhand dealings'. There is an 'illicit' sexual connotation: a left-handed wife' is a mistress; a 'left-handed marriage' is a morganatic marriage, or a sexual liason outside marriage. In the Bible, evil usually comes from the left side, good from the right. The Devil was seen as left-handed, and is often portrayed as such in visual representations. there is an association with witchcraft: in the Black Mass, for instance, witches would hail the Queen of the Sabbath with the left hand. Talon marks, blemishes or moles found on the left side were thought to indicate sorcery, as was left-handedness itself.
Whilst most educated people might not think they make an association between left hand and evil, the potency of long-held traditions dictates otherwise. Indeed, the more recent discipline of criminology has demonstrated its own (sometimes pseudo-) scientific tendencies of stigmatising left-handers by seening us as tending towards the criminal. Lombroso believed left-handers were three times more likely to be criminal, and noted: "The percentage of left-handedness is much higher in the abnormal class of people, eg: mental defective. Insane, incorrigibles, criminals, etc." It was thought, indeed that left-handers were wilfully rebelling against the right-handed 'norm', that left-handedness was psychologically determined, and that it therefore indicated a rebellious or non-conformist nature.
Whether or not these assertions are true is irrelevant. My point is that they were perceived to be true, and that they help explain why the conception of the Ripper as left-handed became so widely accepted. Dr Llewellyn's initial belief that Jack the Ripper was left-handed became absorbed into Ripper lore, a place which it has sustained long after subsequent doctors had disagreed, and Dr Llewellyn himself had retracted his initial statement.

he could have also been able to use both hands as well switching from left to right
because even though they could not figure this out back then but now if they had paid attention back then they would have figured it out right off the bat because the artiral spray of blood would have pointed it out.
say he slashed her neck open from the left?
the blood would then go in that direction
and if he had of done it with his right hand it would have gone to the right. now if he had of came up on her from behind then it would have sprayed out all over the place.

Exactly - I think I read that somewhere that he could have switched hands, but we can never be sure if Jack would have been comfortable with this. I think there is some mention of where the blood sprayed in the autopsy reports - I've made a thread for a couple of the victims so far, concerning this. It's something I can't believe they've not figured out, but I guess it is difficult to say as how the Ripper stood could determine the difference between left and right.

Mordke wrote:

Exactly - I think I read that somewhere that he could have switched hands, but we can never be sure if Jack would have been comfortable with this. I think there is some mention of where the blood sprayed in the autopsy reports - I've made a thread for a couple of the victims so far, concerning this. It's something I can't believe they've not figured out, but I guess it is difficult to say as how the Ripper stood could determine the difference between left and right.

exactly but they would have figured it out at the crime scene right off the bat if there was any arterial spray of blood.

I know there was some definate spray up one of the walls, but since he strangled his victims first, this would have been kept to a minimum. The spray being low down on the wall clearly indicates that their throats were cut on the ground, and he placed his victims down carefully because there was no bruising found at the back of the head. I can assume that he sat in a position to limit the amount of blood splattering up on his own clothes, so either the opposite side to the incision or at the head.

Mordke wrote:

I know there was some definate spray up one of the walls, but since he strangled his victims first, this would have been kept to a minimum. The spray being low down on the wall clearly indicates that their throats were cut on the ground, and he placed his victims down carefully because there was no bruising found at the back of the head. I can assume that he sat in a position to limit the amount of blood splattering up on his own clothes, so either the opposite side to the incision or at the head.

your right i completely forgot about that:(

Wow, I am so bad at my lefts and rights, but if I imagine doing the murders *Produces teddy and joke knife with retractable blade* (Yes, that is important) ... He would have been sitting on the woman's right side, as I found this to be extremely comfortable in slitting the throat, and if I squatted and turned my body slightly, the rip that apparently started at the groin and ended up to her breast could have been done by a left handed killer. If he were to be sitting at her head, (I don't know how awkward it would have been to remove organs by leaning over her head, since my teddy is obviously much smaller than the prostitutes Jack ripped.) then the killer would have been right handed, because of the way the throat is cut and the rips lean.

Mordke wrote:

Wow, I am so bad at my lefts and rights, but if I imagine doing the murders *Produces teddy and joke knife with retractable blade* (Yes, that is important) ... He would have been sitting on the woman's right side, as I found this to be extremely comfortable in slitting the throat, and if I squatted and turned my body slightly, the rip that apparently started at the groin and ended up to her breast could have been done by a left handed killer. If he were to be sitting at her head, (I don't know how awkward it would have been to remove organs by leaning over her head, since my teddy is obviously much smaller than the prostitutes Jack ripped.) then the killer would have been right handed, because of the way the throat is cut and the rips lean.

yeah or he could have propped her up against a wall to do it(the cutting of her stomach i mean?)

I am beginning to come to the conclusion that perhaps he was left handed. I'm guessing he sat to the side, as this would have been easier to cut the bodies for him and reach all the parts he needed to get to. I wonder if there was any evidence of him cutting them against the wall. I must check. Since the bodies were found to have the starting cut at the groin and it veered over to the right, and the mutilations to Catherine Eddowes' face were to the left, the killer must have been sitting on the right side, meaning a left handed killer.

Mordke wrote:

I am beginning to come to the conclusion that perhaps he was left handed. I'm guessing he sat to the side, as this would have been easier to cut the bodies for him and reach all the parts he needed to get to. I wonder if there was any evidence of him cutting them against the wall. I must check. Since the bodies were found to have the starting cut at the groin and it veered over to the right, and the mutilations to Catherine Eddowes' face were to the left, the killer must have been sitting on the right side, meaning a left handed killer.

i agree
but he also could have still been ambidextrous as well meaning it did not matter what side he was standing,because if the mutilations veered to the right and then Catherine eddowes's face mutilation were to the left he could have switched hands so it would have been harder for the cop's to catch him,now this is just a theory though:)

Yeah, and we can't rule anything like that out since we don't know enough about it. But like I said, it is highly probable. Reading a little more about left handers, they are more likely than right handed people to become psychopaths, if this says anything.

Mordke wrote:

Yeah, and we can't rule anything like that out since we don't know enough about it. But like I said, it is highly probable. Reading a little more about left handers, they are more likely than right handed people to become psychopaths, if this says anything.

your right but then wow i must be nuts because i'm left handed lol:)

Same here!! We're both lefties, and hopefully we can add Jack to that as well and make an epic lefties gang! XD lol Jack the Ripper's work must have really been seen as the work of the devil, since it was seen to be wrong if you were left handed in those days. I think there was a lot of hype in the newspapers about their suspicions of him being infamously left handed, if I can remember right.

Mordke wrote:

Same here!! We're both lefties, and hopefully we can add Jack to that as well and make an epic lefties gang! XD lol Jack the Ripper's work must have really been seen as the work of the devil, since it was seen to be wrong if you were left handed in those days. I think there was a lot of hype in the newspapers about their suspicions of him being infamously left handed, if I can remember right.

lol yeah,:)
your right they probably hyped it up

Like they hyped up everything about him... XD Would have narrowed their search down if they knew they were looking for a left-handed serail killer since only one in 10 people are left handed. Still, the facts remain unclear. It would have been interesting to see what hand the writing on the wall was written in, but of course, they didn't photograph possibly one of the two most valuable clues in the investigation.

Mordke wrote:

Like they hyped up everything about him... XD Would have narrowed their search down if they knew they were looking for a left-handed serail killer since only one in 10 people are left handed. Still, the facts remain unclear. It would have been interesting to see what hand the writing on the wall was written in, but of course, they didn't photograph possibly one of the two most valuable clues in the investigation.

exactly,if they had of photographed it they would have possibly figured it out.

It makes me so annoyed that they couldn't have waited just a few hours longer for the sun to rise. Clearly the police were divided, and where as half of thme wanted to note it as valuable evidence, Warren had to scrub it off, just because it mentioned the Jews. I mean, I'm sure they were right to try and prevent the riots, since if they ever found out that Jack the Ripper was Jewish they would have been up in arms, and the subject of the message would have no doubt stirred up trouble. But what they destroyed was a valuable clue that would have no doubt been useful in some way or another, such as now.

Mordke wrote:

It makes me so annoyed that they couldn't have waited just a few hours longer for the sun to rise. Clearly the police were divided, and where as half of thme wanted to note it as valuable evidence, Warren had to scrub it off, just because it mentioned the Jews. I mean, I'm sure they were right to try and prevent the riots, since if they ever found out that Jack the Ripper was Jewish they would have been up in arms, and the subject of the message would have no doubt stirred up trouble. But what they destroyed was a valuable clue that would have no doubt been useful in some way or another, such as now.

exactly,if they really wanted to catch him they should have waited...now this strengthens my free mason theory even more.

Yes, you're right. In fact, it strengthens both of them, which is quite funny! XD *Shakes head in amusement* Well, we both picked the best theories out there in my opinion since they both fit quite snugly with all the clues they had. I think in their minds they were either thinking, "Great, his Jewish, and this is going to go down a storm in Whitechapel" Or they secretly knew that this was something that could have increased their chances of catching him so they scrubbed it off because of conspicacy. This would have meant that for the Free Mason theory, Warren would have been in on it all and this would ensure that anything found would be covered up and long forgotten if it went through him first, making the possibility of proving who Jack was next to impossible.

Mordke wrote:

Yes, you're right. In fact, it strengthens both of them, which is quite funny! XD *Shakes head in amusement* Well, we both picked the best theories out there in my opinion since they both fit quite snugly with all the clues they had. I think in their minds they were either thinking, "Great, his Jewish, and this is going to go down a storm in Whitechapel" Or they secretly knew that this was something that could have increased their chances of catching him so they scrubbed it off because of conspicacy. This would have meant that for the Free Mason theory, Warren would have been in on it all and this would ensure that anything found would be covered up and long forgotten if it went through him first, making the possibility of proving who Jack was next to impossible.

yup,the perfect crime?

The fact that Jack was so careless amuses me. I don't even think he was too worried about getting caught to be honest, and yet he pulled off perhaps the most famous serial killings in British history, even before the term serial killer was invented, on the basis that he was so lucky, blended in so well and commited the crimes in the last glimmer of old school tech before the wave of new advances brought about changes in the criminal world. How he pulled it all off still baffles us, so the Ripper industry lives on. If the killer is ever proven, it will be a massive blow by the looks of things, and I still think people will try to think up alternative theories. Funny how even a simple question of which hand he used is still in debate! XD

Mordke wrote:

The fact that Jack was so careless amuses me. I don't even think he was too worried about getting caught to be honest, and yet he pulled off perhaps the most famous serial killings in British history, even before the term serial killer was invented, on the basis that he was so lucky, blended in so well and commited the crimes in the last glimmer of old school tech before the wave of new advances brought about changes in the criminal world. How he pulled it all off still baffles us, so the Ripper industry lives on. If the killer is ever proven, it will be a massive blow by the looks of things, and I still think people will try to think up alternative theories. Funny how even a simple question of which hand he used is still in debate! XD

your right
it is still very interesting

[quote="Mordke"]I found this on casebook, deeply analysing the case of Jack the Ripper’s preferred hand. Yes, it's long... but interesting...

From the time of the Ripper killings until right up to the present day, it has often been suggested the Jack the Ripper was left-handed. As a left-handed myself, this intrigued me: was Jack the Ripper one of my own? Or was the suggestion that the Ripper was left-handed more of a product of the negative connotations attached to left-handed people, and to the left hand in general, than any hard forensic evidence that the knife wounds and bruising were inflicted by a sinistral killer?
At first the second of these possibilities might seem unlikely, for the suggestion the Ripper was left-handed came from the very best of sources: Dr Rees Ralph Llewellyn, the doctor who carried out the post mortem on Polly Nichols. Dr Llewellyn's findings were summarised by Inspector John Spratling thus:
(...) her throat had been cut from left to right, two distinct cuts being on the left side, the windpipe, gullet and spinal cord being cut through; a bruise apparently of a thumb being on the right lower jaw, also one on the left cheek, the abdomen had been cut open from centre of bottom of ribs along right side, under pelvis to left of stomach, there the wound was jagged; the omentum, or coating of the stomach, was also cut in several places, and two small stabs on private parts; apparently done with a strong bladed knife; supposed to have been done by some left handed person; death being almost instantaneous.
What was it in these details that led Dr Llewellyn to suggest that the killer was left-handed?
Well, his assertion seems to be based on two things: the direction of the knife wounds and the location of the facial and throatal bruising. Llewellyn asserted that the knife wounds ran from left to right. Now this was the case with all the canonical victims, except possibly Kelly, who was so comprehensively carved up that it does not appear to have been noted which direction the neck wound (or wounds) ran in. Whether or not left to right knife wounds indicate sinistrality, however, depends on where the Ripper stood, bent or squatted as he inflicted the wounds.
If they were inflicted from behind a standing victim, a left-handed would inflict wounds which ran from right to left. Forensic analysis, however, shows that this would not have been how the wounds would have been inflicted. The Ripper's modus operandi was to first render his victims unconscious by strangling them. This is indicated by the fact that, in the case of Nichols, discolouration was noted on the face and that, in the case of Chapman, her tongue was swollen and protruding from her front teeth. The point, therefore, is that the knife wounds must have been inflicted with the victim lying on the ground. Conceivably, the killer could have inflicted the knife wounds by standing astride the body and bending over it. This would have resulted in left to right knife wounds from a right-handed killer, or right to left knife wounds from a left-handed killer. This position is unlikely, however: it is uncomfortable, it might result in the murderer becoming covered in blood (from the spurt coming from the severed carotid artery) and it would obscure what little light the murderer might have to work by. It would also lessen his chance of observing anyone approaching him.
The more likely scenarios are that the Ripper inflicted his knife wounds from the victim's side or from behind her head. A left-handed killer would squat by the victim's right side and inflict left to right wounds. Or he would squat by the left side of the victim's head, steadying the head with his right hand and inflicting the neck wounds with his left hand, producing a right to left cut. A right-handed killer would squat by the victim's left side and inflict right to left knife wounds, or to the right of the victim's head, steadying the head with his left hand and inflicting a left to right would with his right hand. My suspicion, however, is that the Ripper squatted at the top of his victim's head so as to face her feet. The reason for this is that the killer could in this way not only steady the victim's head with his non-preferred hand, while wielding the knife in his preferred hand, but direct the jet of blood from the carotid artery away from him. Gripping the face in this way would have been especially important if the victim were still conscious. I am not the first person to form this opinion: Phil Sugden reached it before me.
From this position, then, it would be a right-handed killer who would inflict left to right knife wounds, and a left-handed killer who would inflict right to left knife wounds. This analysis applies to all victims except Mary Kelly. She is a special case because the position of the bed, wedged against a corner wall, compelled the Ripper to work at her left side. (I suspect that the police photographer who took the photograph of Kelly from behind the bed would have had to pull the bed away from the wall in order to do so.)
The facial bruising observed by Dr Llewellyn also gives us a clue to the Ripper's handedness. He recorded that there were bruises on both sides of her face: one, apparently a thumb mark, on the right lower jaw, and another on the left cheek. Sugden suggests this indicates a right-handed attack from the top of Nichol's head, as outlined above. The Ripper would have gripped her head with his left hand, thus forming the bruise on her right lower jaw with his thumb and the bruise on her left cheek with his fingers. He then inflicted the knife wounds with his right hand.
Further indications of the Ripper's handedness can be gleaned from the abdominal mutilations. The most fruitful information on these is to be found in the Eddowes murder, for in, this case we have a great deal of information: there is not just Dr Brown's post mortem report, but full-length photographs and annotated drawings. At first glance, assuming the cut was inflicted downwards, it appears that the abdominal wound veered to the left, indicating a left-handed knife user. In fact, Dr Brown's evidence makes it quite clear that the wound was inflicted upwards from the abdomen towards the sternum. This means the wound veered right, right-handed knife usage. Again someone got here before me. The forensic expert Prof James Cameron examined both photographs and sketches and concluded that the Ripper was dextral: "The incision," he remarked, "drags to the right, as would happen, and is deeper as more viscera is exposed."
I have already said Kelly is a special case. We do not appear to have any record of which direction her neck wounds were inflicted in, but the circumstances dictated that the Ripper worked from her left aide. In her case, therefore, the neck wounds must have run from right to left. the blood spatterings on the wall (from the severed right carotid artery) back up this assertion, and there is a further clue which may point to the final, fatal neck wound being inflicted with the right hand. Dr Phillips, one of the doctors who carried out the examination of Kelly, observed that there was a large quantity of blood on the right side of the pillow and sheet and under the right-hand side of the bedstead. He therefore believed she had been killed while lying further back on the bed and then subsequently moved towards the killer so he could carry out the mutilations. The initial position of Kelly's throat - up towards the corner of the wall - would have made it awkward for the Ripper to inflict the neck wound left-handed: not impossible by any means, but left handedness would have been a distinct handicap in such a position. One further thought: in the main full-length photograph of Kelly, two areas of mutilations are clearly visible on her left arm. The one on her lower arm is especially revealing, for it's direction, whether inflicted before or after her hand was placed across the abdomen, is towards the right. In other words, it could only have been inflicted with the right hand, unless the killer inflicted it sinistrally in an unnatural and extremely awkward position, with his left elbow pointing up towards the ceiling - hardly something he would be likely to do.
All of this points to the inescapable conclusion that the Ripper was tight-handed. Indeed, Dr Llewellyn himself later came to doubt his initial conclusion. A note penned by Chief Inspector Donald Swanson, dated 19th October 1888, records the following: "At first the Doctor was of the opinion that the wounds were caused by a left-handed person but he is now doubtful." Macnaghten, in the Scotland Yard version of his 'Memoranda', also noted: "The theory that the Whitechapel murderer was left-handed, or, at any rate, ambi-dexter', had its origin in the remark made by a doctor who examined the corpse of one of the earliest victims; other doctors did not agree with him."
Why, then, did Dr Llewellyn initially believe that the killer was left-handed? One clue is to be found in the newspaper reports. Both The Times and The Telegraph reported in their issues of 1st September 1888 that Dr Llewellyn believed the Ripper might be left-handed. The Times continued: "He made a second examination of the body in the mortuary, and on that based his conclusion, but will make no actual post mortem until he receives the coroner's orders." Dr Llewellyn concluded that the Ripper might be left-handed before even carrying out a post modern! And when he did come to conduct the post mortem, he had already made up his mind. This bespeaks more of prejudice towards left-handers than the objective, reasoned conclusions of the pathologist.
But why plump for a left-handed killer? Christopher Frayling has shown how commentators on the Ripper case have had a tendency to blame the murders on minority groups. In the case of Dr Llewellyn. I would suggest that left-handers were the chosen minority. But why? What was the association in Dr Llewellyn's mind between murder and left- handedness? The answer is that there is an extremely long association in popular tradition between evil and the left ' hand. The Latin word for 'left' is 'sinister'. The Italian word for 'left' is 'mancini', which also means 'evil' or 'deceitful'. The Oxford English Dictionary defines 'left-handed' as in part meaning 'doubtful', 'questionable', 'ill-omened' and 'characterised by underhand dealings'. There is an 'illicit' sexual connotation: a left-handed wife' is a mistress; a 'left-handed marriage' is a morganatic marriage, or a sexual liason outside marriage. In the Bible, evil usually comes from the left side, good from the right. The Devil was seen as left-handed, and is often portrayed as such in visual representations. there is an association with witchcraft: in the Black Mass, for instance, witches would hail the Queen of the Sabbath with the left hand. Talon marks, blemishes or moles found on the left side were thought to indicate sorcery, as was left-handedness itself.
Whilst most educated people might not think they make an association between left hand and evil, the potency of long-held traditions dictates otherwise. Indeed, the more recent discipline of criminology has demonstrated its own (sometimes pseudo-) scientific tendencies of stigmatising left-handers by seening us as tending towards the criminal. Lombroso believed left-handers were three times more likely to be criminal, and noted: "The percentage of left-handedness is much higher in the abnormal class of people, eg: mental defective. Insane, incorrigibles, criminals, etc." It was thought, indeed that left-handers were wilfully rebelling against the right-handed 'norm', that left-handedness was psychologically determined, and that it therefore indicated a rebellious or non-conformist nature.
Whether or not these assertions are true is irrelevant. My point is that they were perceived to be true, and that they help explain why the conception of the Ripper as left-handed became so widely accepted. Dr Llewellyn's initial belief that Jack the Ripper was left-handed became absorbed into Ripper lore, a place which it has sustained long after subsequent doctors had disagreed, and Dr Llewellyn himself had retracted his initial statement.

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To me, having her throat cut left to right signifies that Jack is right handed, being right handed myself, that makes sense.

It all depends on which way he is standing really, becuase any hand could have things supporting it. The prostitute's left on the neck would be Jack's right if he's looming over, but if he's hovering over the head, then the prostitute's left would have been Jack's left. The killer was right handed if he cuts with the head closest to him, bet left if he cut with her body closest to him. I'm still confused and would love to have seen CCTV footage for this lol.

Many sinistral males(myself included) learn to perform repetitive tasks with the right hand simply because so many things are manufactured for righties, who are much more fixed in their preferences. Lefties are much more adaptable to circumstances due to their superiority over the tyrannically insistent do-it-our-way righties.
After determining that, I don't know if there is enough evidence extant to determine Jack's handedness.
Cutting off the blood supply to brain which can be done with as little as 4 pounds of pressure can result in unconciousness(not death)in a matter of seconds. Death takes longer. The heart still beats and can still result in a nice arterial spray. Cutting off the air precludes vocalization, an important consideration.
If a strangle attack is postulated to preceed the butchering, the direction of collapse might determine the position of the attacker if efficiency were desired.
All hypothetical, of course.