FAIRFIELD — Fairfield University Public Safety officers caught a teenager trespassing on campus while they were breaking up a party in the early hours of Sept. 16, according to town police.

Liam Robertson was allegedly spotted by campus police outside the town houses on campus, despite a trespassing warning issued last September. When a university officer attempted to stop the 18-year-old, he threw a bottle of alcohol at the officer’s feet and ran.

Public safety officers took Robertson into custody, and when they asked for identification, he told them it was in his wallet, according to police. Security officers found a Sacred Heart University ID identifying Robertson, as well as foil containing a white powdery substance that tested positive for cocaine.

Fairfield police charged Robertson with criminal first-degree trespassing and possession of narcotics. The resident of Round Hill Road in Fairfield was released on a promise to appear ahead of his Sept. 30 court date.

Lweiss@hearstmediact.com; @LauraEWeiss16