NORMAN, Oklahoma - Police have issued a Silver Alert for a man and woman last seen walking away from an apartment complex in Norman on Tuesday.

Authorities are on the lookout for 59-year-old Robert Osbourn and 57-year-old Bertha Peppiatt. The pair was last seen on foot near 1878 W. Robinson St. around 11 a.m. on Jan. 30.

According to police, Osbourn has autism, is medically dependent and suffers from kidney failure. Peppiatt is “developmentally delayed”, according to police. Police say Osbourn and Peppiatt refer to themselves as a married couple, although the two are not legally married. And police say they have a history of befriending people who take advantage of them.

Osbourn is described is a white male, last seen wearing a black jacket with white stripes on the sleeves, a T-shirt and blue jeans.

Peppiatt is described as a white female, last seen wearing a plaid peacoat and jeans.

If you have any information regarding their whereabouts you are asked to call 911 immediately. Both are under proven medical or physical disability and are in imminent danger if serious bodily injury or death.