Police say an elderly man who was found dead in his Opotiki home died of serious head injuries and the attack was especially violent and cowardly.
Police have completed a post-mortem on John Alan Rowe, 78, whose body they found at his Windsor Street home, after being alerted by a neighbour on Tuesday morning.
Detective Inspector Rob Jones says the attack was violent and cowardly and took place in the man's bedroom.
Mr Jones told Checkpoint on Thursday Mr Rowe was a relatively frail man who lived on his own.
He says police have upgraded their inquiry and are being assisted by a specialist search team from Auckland.
Personal property has been removed from Mr Rowe's home and police have located some items in nearby streets.
Mr Jones is appealing to the public to contact Opotiki police if they have any knowledge of the attack, and says more than one person may have been involved in the attack.
Thirty police from the Eastern Bay of Plenty and the wider police district are working on the case.