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Det Ch Supt Gordon Lang: "If you see James Allen, dial 999"
A man being sought over two murders in the north east of England knew one of the victims, police have said.
More than 100 officers from Cleveland and North Yorkshire forces are involved in the search for James Allen, 35, originally from Blackpool.
It follows the discovery of the bodies of Colin Dunford, 81, in Middlesbrough and Julie Davison, 50, in Whitby.
Cleveland Police said Mr Allen had lived next door to Mr Dunford about 12 months ago.
At this stage, officers do not think he knew Ms Davison.
The force said a key line of inquiry was a black bike which was seen outside both murder scenes.
Mr Allen is known to police and is currently on bail. They advised people not to approach him but to contact them immediately.
Julie Davison and Colin Dunford both died from head injuries
Temporary Det Ch Supt Gordon Lang, of Cleveland Police, said: "We also believe that Allen may have been involved in a number of other offences, and these potential links are currently being investigated.
"He is known to police and he has a history of committing violent offences."
Mr Allen is described as 5ft 7in (1.74m) tall, with a bald head and tattoos on both arms.
Head injuriesEarlier, Cleveland Police went to a house in Lothian Road but it is thought Mr Allen was not there.
The road was cordoned off but later reopened.
Lee Johnson, from BBC Tees, said a number of police officers were guarding the house, which it is believed Mr Allen had been living in.
He said forensic officers had taken items out of the house and loaded them into a van.
Lothian Road was cordoned off while police went into the house
One man, who lived two doors away, said he believed Mr Allen had lived at the house for about a month.
Mr Dunford's body was found at his home in Leven Street on Monday night.
Police said a post-mortem examination revealed he suffered serious head injuries as a result of a significant assault.
Ms Davison was found at a flat in Church Square, Whitby, on Wednesday. She had also suffered head injuries.
Police said Mr Dunford and Ms Davison did not know each other.