Police in Philadelphia are looking for a man who apparently attacked a Temple University professor in his office just before noon Tuesday.
Philadelphia police have released a surveillance photo of the suspect.
The attack took place in Anderson Hall, a classroom building for the humanities around 11:20 a.m.
Police said the 81-year-old professor was alone in an open office area when he was attacked from behind.
Police said the suspect punched the professor in the face, held a knife to his throat and demanded his wallet.
After taking the victim's wallet, the man hit the professor again.
Police said the victim suffered lacerations to the face and head, as well as swelling and bleeding on the brain.
There's no word on the victim's condition.
Anyone with information is asked to call Philadelphia Police's Special Investigation Unit at 215-686-3047 or submit a tip to the police tip line at 215-686-TIPS (8477), email to tips@PhillyPolice.com or text to PPDTIP (773847).
Police warn if you see this person, do not approach him, but call 9-1-1.