AT 8.40am on Wednesday, December 28, 2016, a man and a woman boarded the 999 bus at Fremantle train station. After a few minutes police say the man was seen on CCTV footage using a marker on the back of the seat in front of him. The pair got off the bus on Barry Marshall Parade in Murdoch. Police want to speak to the two people pictured about the incident. The man is described as being 27 to 35 years old with a medium build and wearing a dark jumper, blue and grey shorts and a beanie. The woman is described as being 25 to 35 years old with a solid build and wearing dark clothes. Anyone with information is asked to call Crime Stoppers.