Police are appealing to anyone who saw Mr Ross around the Towey St or Arun St areas between 7pm on Friday and 5pm on Saturday.
It is believed he may have had contact with members of the community or made purchases at shops before to going to the Arun St address, police said.
Mr Ross was described as being of medium build, about 178cm tall, and was wearing blue jeans and a two-tone blue chequered jacket with wool skin lining and collar.