Police in Wiltshire are trying to discover how a 41-year-old man suffered serious head injuries.
The man was found in High Street, Purton, just before 0700 GMT on 12 February by a passer-by. He was then taken home by someone who knew him.
He was later taken to hospital and is now in a "stable" condition.
Police believe he visited several pubs on Friday and he was seen leaving the George Inn at 0200 GMT on Saturday but officers are unsure what happened next.
"The man has been transferred to John Radcliffe Hospital in Oxford where his condition is described as stable," a Wiltshire Police spokesman said.