SYRACUSE, N.Y. (AP) — A jury has convicted a New York prison inmate of falsely filing tax returns seeking $890 million in refunds.

Prosecutors say the man filed the bogus returns from 2006 to 2010 while at various state prisons. They say he even was issued a refund for $327,000 — but prison officials intercepted the check and returned it to the Internal Revenue Service, which led the investigation.

The man was convicted Thursday of 11 counts of filing false claims and one count of helping another inmate file bogus returns.

He was serving two to four years for possession of stolen property when he was charged last February. He faces up to five years in prison and a fine of up to $250,000 on each count when he’s sentenced in May.