Police think the same man is responsible for five unsolved sex attacks on teenage boys in Ferntree Gully, in Melbourne’s outer-east.

They want public help to find the man, who abducted a 16-year-old from the Heatherdale railway station in 1984.

The teen was given alcohol, threatened with a knife and assaulted.

Police say they have reviewed four similar cases and they think the same man attacked boys in the area between 1980 and 2004.