Conditions for executing body-switching with the following sequence of events:

  1. Maintain at least 10 seconds of direct eye contact.
  2. Must be in close proximity of the target, maximum distance is 10 meters radius.
  3. Works with reflection however must maintain eye contact and success is proportional to the quality of the reflection with the longest time estimated at most 900 seconds.
  4. Target is then hypnotized and will assume new fake memories in the now vacated body so that s/he would not freak out or stand out from the crowd for at least 24 hours.
  5. These fake memories cannot be revoked by the target while the effect lasts.
  6. This ability cannot be tutored.
  7. User retains their original personality and memories but no recollection of target's memories.
  8. After execution the transfer is permanent.

Suppose there is a vengeful psychopath craving immortality and enjoys instilling suicidal thinking into unsuspecting people, how can the police identify and capture this body-switcher and put this entire madness to a halt?

Answer with the least collateral damage, fastest time to apprehend and correctly identify the accused and the body-switching ability (must be a concrete evident) wins.

Defeat condition: this will result in the death of body-switcher by normal means of dying including aging.


closed as off-topic by Aify, Hohmannfan, MichaelK, TrEs-2b, SJuan76 Sep 25 '16 at 21:13

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "This question does not appear to be about worldbuilding, within the scope defined in the help center." – Aify, Hohmannfan, MichaelK, TrEs-2b, SJuan76
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  • $\begingroup$ I don't understand point 4, what do you mean by assume new fake memories and what happens to the users original body? $\endgroup$ – Skye Sep 25 '16 at 5:26
  • $\begingroup$ @Skye: suppose I'm switch body with u and I will automatically instill fake memory to you so that you wont attract unnecessary attention to yourselves. I will then steal you body and flee or find another victims and implant fake suicidal memories again. $\endgroup$ – user6760 Sep 25 '16 at 5:29
  • $\begingroup$ your body then? Does your body just flop onto the floor and die? $\endgroup$ – Skye Sep 25 '16 at 5:30
  • $\begingroup$ @Skye: Don't worry there is absolutely no side effects, my victim will simply believe s/he is going to find a secluded spot and commit suicide while I allow this vicious cycle to go on forever hopefully. $\endgroup$ – user6760 Sep 25 '16 at 5:33
  • $\begingroup$ I'm sure someone would notice if you stared into a person's eyes for 10 seconds, the easiest place I can think of to pull this off is on the public transport where you can seat on those seats that face someone else. $\endgroup$ – Skye Sep 25 '16 at 5:35

Even though this is tagged "magic", I'm just going to assume "extra-sensory" is not magic for this purpose because I do not really see a need for it is this case. As far as I can see magic only really complicates things and makes more to explain into/out of in this case. I can expand on that in answer to a different question if you like. :)

Assuming that there is the possibility of telepathic ability, then you must have another telepathic/other-sensory person first sense, locate and track the behaviors and thought processes of the "suspect". The closest example I know of for a scenario like this is in the movie Suspect Zero. In that case an ex-government-research-projects subject was involved in military "psy-ops" (psychic operations, presumably for remote spying) to produce and control states of mind in which the subject could project into space and view events/scenes from other locations. As far as I recall this did not involve directly sensing the mind or thoughts of other individuals, i.e. the suspect, but rather identifying and following a pattern (or lack thereof) based on various disappearances. Basically, using astral projection to review/search/cover an area in a region central to the disappearances, searching possible routes and eventually, meticulously tracking possibilities back to some kind of hot spot/region before discovering the location and evidence of the activities of the suspect, referred to as in the title as suspect zero due to the overall lack of a pattern for the crimes.

Here you have a similar concept, but a rather different situation. However, this would seem to involve more drama, revelation of inner agony, torment and certainly as much thrill as you want. Why do the people then want to die? What does the suspect "do" to them? Focus on that, it will take plenty of explaining to get that to work well. And not only do you have to deal with a single event/victim at a time (meaning active threats, things to consider, deaths), you have, at first, a string of suicides and evidence, then as you get closer, a collection, perhaps only a small collection, of terribly disturbed people who are being protected from themselves. Identify who the suspect likes to target and filter the mental spaces to focus on those people first. Get into their heads and help to draw them away from the suspect. Close his mental doors and put pressure on him. Find a team of ex-government hires who do psy-ops or similar and a monk or some other odd figures and have them work together to corner the suspect. When he has no way out of the body, then you can have foot soldiers chase him down when all of his mental exits are blocked.

  • $\begingroup$ +1 Interesting approach, I incorrectly tagged magic because I'm unable to find a suitable tag but anyway I'm working on ambush and bait then apply game theory to nail the culprit because his weakness is he never contemplate suicide. $\endgroup$ – user6760 Sep 25 '16 at 7:34
  • $\begingroup$ @user6760 I loved that movie. This would be a very nice story indeed. :) $\endgroup$ – Nolo Sep 25 '16 at 7:47
  • $\begingroup$ @user6760 To clarify, I meant a "single event" at a time, meaning protect a single person, but you may have several once the story heats up. $\endgroup$ – Nolo Sep 25 '16 at 7:52
  • $\begingroup$ No worry, great mind thinks alike. $\endgroup$ – user6760 Sep 25 '16 at 7:55

Hmm... How about this for one possibility:

Assume you have your group of volunteers (probably police, but you can maybe extend some of this to the public).

-give them each a security code (bank style where you only ask for parts of it, to avoid compromising it by the bad guy overhearing). Since the swapper only has his own memories, if someone knows their password you can assume it's the same person as when the password was set up. Now you can check whether someone's swapped in since then when you catch the suspect.

-if possible, fit your volunteers with a covert pack that needs regular coded responses but isn't obvious that they're using it (maybe press the right buttons on a device in your pocket) or injects them with a rapid knockout drug and signals for help. Then you stick a bag over their head, to prevent eye contact, bring them round, and check their password to see if they just goofed or you've caught your target.

-Then send your volunteers out to the suspected location of the bad guy, like a normal undercover bait operation. Or set something up to attract the bad guy to try and possess one of your volunteers - maybe a local reporter that "lets slip" that they're going to attend a special closed conference on how they're planning to deal with the bad guy, or similar...

-Or (maybe simpler) set up the conference, issue people passwords well in advance before you make it public (and DON't have any written stuff that might tip off the possessor), publicise it well in advance, get people in, seal the exits, tell them not to make eye contact, then move them out one at a time, check their passwords, and see if the bad guy attended.

Once you have the bad guy, you can force him to transfer to a condemned prisoner - or cycle him round between prisoners (offer them a 2 week cut in their sentence for one week of possession).


Identification is complicated, but I'd like to think some help from the NSA would do the trick. We don't know 100% what they have behind those closed doors, but most agree that they have supercomputers tailored for identifying unusual and dangerous behavior. The inability to access memories would make it very hard for the body-shifter to switch to someone they don't know without leaving some shift in digital behavior.

This would be much harder if the body-shifter took the time to get to know the victim. In fact, it may actually be impossible in such a case. In fact, a trivial solution to vanish forever would be to find someone just about to enter Witness Protection and inhabit them!

As for capture, have you considered relying on blind people to identify and restrain the body switcher? They could have an escort of seeing individuals to help them (blind people are astonishingly independent, but there are some things where sight it essential. Driving a car is one of them). Once it is believed that the group is within the seeing people should shut their eyes (eyesight is a liability now) and let the blind people do the astonishing things they do. They often have heightened awareness in directions we don't think of. They would likely be able to identify quirks of the body-shifter by sound or by touch (especially touch).


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