Marcelo Perez, 31, of the District, pleaded guilty Tuesday to sexually abusing a teenaged girl in 2009, authorities said.

At Tuesday’s court hearing, Perez admitted to sexually assaulting his girlfriend’s daughter, whose name was not released, at an apartment in Northwest Washington, the U.S. Attorney’s office said in a statememt.

Perez had been living with his girlfriend and her family for several years at the time of the assault, prosecutors said. Perez admitted assaulting the girl, who was 15 at the time, late at night, when no one else was at home.

Perez, charged with first-degree child sexual abuse, will be sentenced Nov. 4 and faces up to 30 years in prison.