West Yorkshire Police are concerned that a missing Leeds man may have "come to some harm".
The force has been searching for Artur Rej, 41, in Harehills for seven days and say his disappearance is "completely out of character".
They have searched houses on several streets, including Sandhurst Road, Lowther Street and Cowper Mount, and arrested three men, who have been released under investigation.
Forensic investigators have also been seen in the area.
Detective chief inspector Tony Nicholson said: "While this remains a missing person inquiry, given the time that has now passed since he was last seen and the lack of contact with his family and friends, we are having to consider the possibility that he has come to some harm.
“Artur is well known in the area, particularly within the Lithuanian community of Harehills, and we need people to come forwards if they have any information about his movements or whereabouts since early January.”
Anyone with information is asked to contact police, quoting reference 13200105936, or use the police's Live Chat Facility.
