Police are now appealing to the public for information to trace the 39-year-old who was last seen in the Orbiston area of Bellshill, North Lanarkshire, at 8pm on Sunday January 24.
Mr Bertram is described as 5ft 11in, with short brown hair and a medium build.
He was last seen wearing a black 'Scruffs' hoodie and hat, black cargo trousers and black trainers.
A Police Scotland spokesperson said: “We are appealing for the public’s help as part of our efforts to trace a 39 year old man, Andrew Bertram.
"There are concerns for his welfare.
“Anyone who may have seen Andrew since this time, or who has any information on his whereabouts, is urged to contact Police Scotland via 101 quoting "incident number 3133 of the 25/01/21".