If after committing a crime the guys goes to jail, it won't have a plural form, or at least the plural form will be used less often. It has a plural form as in the following example: Property crime is a category of crime that includes, among other crimes, burglary, larceny, theft, motor vehicle theft, arson, shoplifting, and vandalism.

"Crime" can be countable or uncountable, so when countable it can be plural. He committed many crimes, so he was sent to jail.