Forensic testing. Bullets fired from the weapon can be matched to those found at the crime scene. Shell casing can also be matched up.
However, if the gun wasn't fired, it would be close to impossible to prove that it has been used to commit a crime.
That person has obviously never heard of paper patching,using a rifle of revolver,or cleaning your gun...Creativity triumphs over technology anyday...
Contact your local law enforcement.
Computer crime has been defined as 'any illegal act fostered or facilitated by a computer, whether the computer is an object of a crime, an instrument used to commit a crime, or a repository of evidence related to a crime'
If it has lines carved in the grips...
Unless it has markings you can't. Many kukris or Khukris have been made in India since the 1940's for tourists and for sales to the West. Traditional Khukris have been made in Nepal by hand for centuries, of hand hammered carbon steel.
You can tell when a dildo was used if you saw someone using it.
easy ,the person could have been allergic or worse
The clock has been used to tell time on ships for centuries.
There are many ways - such as... Entry & exit wounds on a corpse, powder residue, bullet holes at the crime scene, rifling (on any recovered projectile).
if it has no money on it
A crime?
I used a hand gesture to tell the man to come over here.
Recidivism (apex) :)
Y Only if it has been stolen/used in a crime and entered in the database.