BERKELEY -- Someone etched a swastika and two phallic symbols on a housing complex door at the University of California, Berkeley, the third hate-related incident reported in the past three weeks, police said.

The etching was found by a residential adviser in Building 7 at the Clark Kerr Campus Housing Complex, according to police. Authorities believe the incident occurred Sept. 1 between 4:30 a.m. and 11 a.m.

Days earlier in the same housing complex, someone wrote a homophobic phrase and drew a phallic symbol on a flier promoting cleanliness inside a unisex bathroom, police said. The incident occurred sometime between Aug. 24 and Aug. 28.

In a third incident on Aug. 14, a university custodian found a racial epithet written on classroom chalkboard in Wheeler Hall. The custodian told police he believed the comment was directed at him, and possibly written by two people he earlier asked to lock up the classroom. Police do not believe the incidents are related. They remain under investigation.

David DeBolt covers breaking news. Contact him in Richmond at 510-262-2728. Follow him at Twitter.com/daviddebolt.