The Delaware County Medical Examiner's office has ruled the death of an Interboro High School student a suicide.

Dominic Marchesani, 18, of Prospect Park, was found hanged Wednesday night in an old mill on the 2500 block of Ridley Avenue in Chester City, according to police.

Police said that around 7:30 p.m., Marchesani's parents went looking for their son at the rental space where the young man's band had been practicing. He was pronounced dead at the scene by medics, police said.

The high school has lost four students in the last two months. On Jan. 19, William J. Bradley, 17, a junior, was accidentally killed as he rode his bicycle on South Avenue in Glenolden. On Feb. 25, sophomores Vanessa Dorwart, 15, and Gina Gentile, 16, were struck by a train at the Norwood station. The girls' deaths also were determined to be suicides.

Contact staff writer Mari A. Schaefer at 610-892-9149 or mschaefer@phillynews.com.