Police are hoping surveillance video will help them track down a man wanted for sexually assaulting a woman on a Bronx rooftop this past weekend.

Investigators say the man seen riding the scooter approached a 21-year-old woman early Sunday morning and told her he had a knife.

They say he forced the victim to a rooftop landing of a building on Bayner Place in Soundview and attacked her.

The woman's iPhone and purse were also stolen.

Investigators say the suspect has a rash on the right side of his face.

Anyone with information on the case should contact the Crime Stoppers hotline at 1-800-577-TIPS, or text CRIMES and then enter TIP577, or visit www.nypdcrimestoppers.com.