Criminal use of firearms silencers
A study from the Western Criminology Review. Most suppressor crimes are for the act of owning a suppressor for which you have not paid a tax. Not paying the tax will land you in jail for 30 years. Seems awful cruel and unusual for tax evasion.
I only know of one instance in which a suppressor was used in an actual shooting. And that suppressor, if memory serves, was stolen.