Officers investigating a serious assault in York say they've seized a hammer for forensic examination.
A 45-year-old local man, is currently in a coma at York District Hospital.
A 47-year-old man and a 45-year-old woman who were arrested in connection with the incident have been released without further police action. A 25-year-old woman and 56-year-old man who were also arrested remain in police custody.
Inspector Ian Dyer, of York CID, said: "I am appealing to anyone who knows anything about this incident to come forward.
"A man is seriously ill in hospital and we need to establish how he came to sustain his injuries.
"I am urging anyone who witnessed the assault or was in the Walmgate or Lawrence Street areas between 5pm and 7pm on Tuesday 27 March 2012, to get in touch with the police or Crimestoppers."