After two reports of sexual assault at UC Berkeley fraternities in as many months, a third attack has allegedly occurred, reports ABC 7.

Campus police received an anonymous letter describing the alleged incident, this one at a frat house Halloween party on Piedmont Avenue. Eight of Berkeley's recognized fraternities are located on the street. Yet police say they are unable to proceed until a victim comes forward.

The previous two sexual assaults allegedly involved date rape drugs and fraternities. Last month, an arrest was made, but the suspect was exonerated and charges were dismissed, reports Berkeleyside.

The University of California Police Department’s annual report cites reports of 33 forcible sexual offenses involving students on campus and public property in the last year, with 23 in 2012 and 45 in 2011.

Colleges are officially on notice, as scrutiny for campus rape, assault, and related administrative policy has reached new heights. California's groundbreaking “yes means yes” or “affirmed consent” law was signed into law in September, just in time for the academic year. Should the victims in any of these cases come forward and press charges, it will put the new law to the test.

Previously: One Man Charged So Far In String Of Sexual Assaults At UC Berkeley Fraternities