Rockingham police acting Senior Sergeant Dana Rigoir said they were investigating last week’s incidents.
“We are trying to ascertain if there was any CCTV at the train station,” she said.
The person of interest was described as 14-18 years old, about 177cm tall, with dark skin.
Police claim the teen performed obscene acts twice at Rockingham Train Station and twice at Mandurah Train Station.
Call Crime Stoppers on 1800 333 000 with information.