A detainee at Cook County Jail has been indicted on a new assault charge after officials say he exposed himself to a female correctional officer.

A grand jury on Wednesday indicted Matthew Jackson, 29, on an aggravated assault charge, according to the Cook County Sheriff’s Office. He’s also charged with misdemeanor public indecency.

Matthew Jackson | Cook County Sheriff’s Office

The charge stemmed from a May 1 incident, when a correctional officer was escorting Jackson to his housing location, the sheriff’s office said. While walking next to her, he exposed himself and “engaged in lewd conduct in the direction of the correctional deputy.”

When she ordered him to stop, Jackson started walking toward her, still exposed, the sheriff’s office said. He stopped when another deputy showed up, and was taken into custody.

Since the start of 2017, there have been more than 620 incidents at Cook County Jail, the sheriff’s office said.