A man’s quest to convince a judge to vacate his 1993 murder conviction based on newly-discovered evidence hit a snag Monday, when a Queens County prosecutor read a letter in court in which the man seemed to implicate himself.

Anthony Nwobi, 52, a Nigerian immigrant from Queens, has spent more than 21 years in prison for the murder of Justin Eze, his childhood friend. Nwobi has maintained Eze’s killer was actually Gregory Reece, the prosecution’s prime witness and owner of the home where the fatal 1992 shooting took place.