Detective Equipments:

> A laser, I don't know what to call it.
-Basically, a detctive throws it on a wall, that shoots a non-damaging laser (would it be invisible????).
-When someone cross the laser, either of 2 things occur (depending on how it'd get balanced):
A) A the device would record a trip, like a trip-meter, which counts how many times its been tripped.
B) Whoever crosses it gets logged on the device, by name, which the detctive can check. (B2: It also shows how long ago they crossed it)
Terms:
-If option B) becomes the device, then it would record the order of whoever crossed it, so if Ben crossed it first, then Thomas and then Ben again, it would show Ben>Thomas>Ben.
-Alternatively, it only shows everyone's name once, and any old records of that person are bumped up to the top of the trip-list.
-People in disguise do not get recorded/trips the meter.
Device Lifetime:
-The device would cease working upon, depending how this device gets implemented: when a detective checks it, when it gets shot/destroyed, when its charge or timer runs out (to prevent eternal trip-laser.)

Any good? I think I made a wall of text here.