Portland police are seeking the public’s help in locating a missing man whose medical condition may have altered his mental state.

Robert Koch, 52, left his home at 723 Riverside St. on Friday at about 8:30 p.m. and said he may be going to the Riverton Trolley Park at Forest Avenue and Riverside Street. The area of the Trolley Park was searched, but Koch was not found.

Koch may have been seen at the 7-Eleven store at Forest and Riverside at 4 a.m. Saturday.

He is described as a white man, 5-feet-8-inches tall, weighing 158 pounds. He is balding with brown hair on the sides and back of his head and has a full beard and moustache. He was wearing blue jeans, a long-sleeve maroon shirt with a gray T-shirt underneath and a white baseball hat.

Police and family members are concerned for his well-being and ask that anyone who may have seen him call the police department at 874-8575.