Police searching for a man suspected of killing two people in their own homes believe he may be trying to change his appearance.
James Allen is being urgently sought by police following the separate murders of Julie Davison, 50, in Whitby, North Yorkshire, and 81-year-old Colin Dunford in Middlesbrough.
Allen, 35, has previous convictions for violence and has served a custodial sentence, Detective Chief Superintendent Gordon Lang told a press conference in Middlesbrough.
Mr Lang said sightings of Allen in the Cleveland and North Yorkshire Police areas were continuing to be reported as well as potential sightings in Leeds on Thursday and Friday.
The detective said it was possible that Allen was trying to change his appearance by growing his hair.
Mr Lang said: "We are investigating a number of sightings in both force areas that have been reported to us, including sightings in the Harehills area of Leeds, and I would repeat our message in urging members of the public if you see James Allen to call 999 immediately.
"This operation continues on a 24/7 basis and it will do until we trace and arrest James Allen."
Mr Lang urged anyone who knows where Allen is to contact police.
"Someone must know where he is. He will have confided in someone and I would appeal to that person to come forward and get in touch with us," he said.
"Two innocent people have lost their lives and it is absolutely vital that we catch James Allen as soon as possible."