A 22-year-old man was arrested yesterday in the rape of a New York City nun whose body was slashed with 27 crosses. Police, acting on a tip in the arrest, said he confessed because he feared the revenge of an outraged Mafia.

The suspect, identified as Harold Wells, a former Chicago resident, was seized as he and a girlfriend stepped off a bus at a downtown bus terminal. He named an accomplice in the attack, police said. A second man was in custody and was being questioned, but police would not say if he is the one Wells named.

Sgt. Thomas Kelley said after officers read the suspect his rights, he confessed to the Oct. 10 attack in an East Harlem convent and told authorities he had fled New York for fear of his life.

"He told us he wanted to talk about it," Kelley said. "We told him he didn't have to. He said he was in fear of his life, that the New York Mafia had offered a $25,000 contract on his life. He fled to Chicago to save his life." Police have been unable to confirm that such a contract existed.

Kelley said police seized the man after New York authorities called their Chicago counterparts to report they believed the suspect was headed for Illinois.