system
Given the following post, respond as if you're commenting on Reddit:
human
[Harry Potter] Could you cast the Imperius curse on someone and force them to take their own life, making it look like suicide, and get away with it?

I guess the more general question is: what are the signs (if any) that a particular curse has been cast on a person after it has worn off? Are there magical traces left which are detectable?
gpt
Conditional yes.

The Imperius curse is an utter bastard to resist. Actions that run particularly contrary to the nature of the creature are a bit easier to resist - and nothing is more inherent to a creature's nature than the urge to keep on breathing. Unless you're a Thestral, anyway, and then your most basic urge is less about living, more about terrifying school children.

So, a subject of sufficient will can resist the urge to kill themselves, but 99% of the folk under the Imperius curse can't. Most of the time, subjects are tormented until they're no longer of use, forced to strangle their families, then go pick a fight with a bus.

Forensic magic is a strange field. If they have access to the wand of the curse caster, they'll know. They can work backward through the spells its cast (with difficulty increasing further back in time) until they work out what's going on. If a magical forensics team is on site when the curse is broken (by death or countermagic) they've got a good chance to know what's happened. The longer period since the curse has been broken, the less chance they have to detect magic in use in the area, let alone the spell (although something as unpleasant as the Imperius curse does leave some strong traces).

The problem with magical forensics is that it is: A) Inexact by its very nature, because Magic is a whiny bitch that hates being looked at by ANYONE, let alone a wizard, B) Dependent on the spell in question for the level of detail, length of time the traces linger, knowledge of the caster/target/effects, etc and C) Dependent on the knowledge, ability and raw strength of the Forensics Examiner.