He is guilty of theft.
I’m a bit confused as to why this is “furti” (thefts) and not “furto” in the singular? My dictionary has it used in the singular?
I would like to hear the thoughts of those further along in their studies than me 
Ciao. In italian I often see a singular expressed in the plural, pe (per esempio) “Hai avuto NOTIZIE da lei?” - Have you had any news from her? but “È una brutta notizia?” Is it bad news?
I read “furti” here as he is guilty of theft in general and not “a theft”. (As always, happy to be corrected).
Grazie per sempre Floria7! 
I appreciate you taking the time to reply.