The 25-year-old was last seen at an address on Rosemore Road in Rosebud about 11am on Saturday (7 October).
He is described as being 175cm tall, with blue eyes, long dark curly hair, and a slim build.
Tristan also has a distinctive tattoo on his right wrist of angel wings.
Police and family have concerns for his welfare as he has an existing medical condition and his disappearance if out of character.
Police have released an image of Tristan in the hope someone recognises him and can provide information on his current whereabouts.
Anyone who sights Tristan or has any information on his whereabouts is urged to contact Rosebud Police Station on 5986 0444.
Source: Victoria Police News – Tuesday, 10 October 2017
