Aftab Khan was arrested in Massachusetts May 13 during the investigation of the failed bombing attempt by investigators who said Shahzad's name was in Khan's cell phone, the New York Daily News reported Saturday.
Shahzad's name was also written on an envelope found in Khan's apartment, authorities said.
Khan came to the United States last summer to marry an American soldier he met overseas, his attorney said, but she broke off the engagement.
In November, Khan married a teacher in Cambridge, Mass., the Daily News said.
Khan, a gas station attendant living in Watertown, Mass., has 30 days to appeal the decision handed down in Boston by Judge Robin Feder.