Police have arrested the man they believe sexually assaulted a West Chester University student in a campus library Wednesday, according to the school. The incident was the fourth alleged sexual assault reported on campus in a month.

In an alert sent to students Thursday night, the university's office of public safety said a man had been charged, but they did not release his name or specify the charges.

Officials said a student reported she was at the Frances Harvey Greene Library Wednesday afternoon when she noticed an older man lurking in nearby bookshelves and staring at her. A few minutes later, she felt something touch her leg, looked down, and saw the man had his hand on her thigh, the police said.

The man apologized, said he was looking for an electrical outlet, and left, the police said.

In two previous sexual assaults reported at the university - one March 30 and a second April 4 - women reported they were sexually assaulted by men they knew. In a third, a female student said she was sexually assaulted in a campus residence by a man she did not recognize. That case is still under investigation.

A university spokeswoman has said none of the incidents appear to be related.

- Tricia L. Nadolny