Police have described the disappearance of a Birmingham man whose mobile phone was found on grassland near his home as "extraordinary".
West Midlands Police said officers were becoming increasingly concerned for the welfare of 45-year-old David Wilkinson, who went missing from his home in Bournville last Sunday.
The disappearance of Mr Wilkinson, who lives with his elderly mother, is described by police as totally unexpected and extensive checks and inquiries have failed to locate him.
Detective Inspector Richard Mayhew, who is heading the search for Mr Wilkinson, said officers had found Mr Wilkinson's phone on Tuesday night on a recreation ground 500m from his home in Mary Vale Road.
The detective said: "This case is extraordinary in that Mr Wilkinson has never been missing from home before and is devoted to his elderly mother, with whom he lives.
"On Sunday night he had been out socially with a friend and there was nothing in his demeanour to suggest he would go missing after returning home.
"He is a conscientious full-time worker and no-one is aware of any problems or issues that may have been troubling him."
The officer added: "He doesn't appear to have taken anything with him from his home and his car is still parked there. We are concerned that we have found his mobile phone in the recreation ground and it is unclear how it came to be there.
"Our appeal is for Mr Wilkinson to make contact with his family or with officers at Bournville Lane police station so that his safety and welfare can be vouched for."