Dzhokhar Tsarnaev, the surviving suspect in the Boston Marathon bombings, is awake in a Boston hospital and responding in writing to questions, a law enforcement official said Sunday.

Investigators who have been waiting to interrogate Tsarnaev are looking into the possibility that his neck wound was self inflicted, a federal law enforcement official said.

The official, who has been briefed on the matter but is not authorized to comment publicly, said that suspicions of a suicide attempt before he was captured center on the small appearance of the entry wound and larger exit wound area