Cops search for suspect in sex assault

Police are searching for a man who sexually assaulted a woman Friday after following her from a train station.
According to police, the man followed his 18-year-old victim to East 187th Street. They say he pulled out a box cutter, threatened her and then sexually assaulted her in a courtyard.
Anyone with information is asked to call Crime Stoppers at 1-800-577-TIPS.