The San Mateo County coroner's office had been having difficulty tracking down the girl's identity since a couple walking along San Gregorio State Beach Sunday afternoon spotted the body.
Following media reports this week, a student at Albany High School told a school administrator Thursday that the unidentified body resembled a missing classmate.
Qiu, 16, had been missing out of Richmond since Sept. 29, Richmond police Lt. Bisa French said.
A coroner's deputy was contacted and the coroner's office was able to confirm the body using information from Richmond police and Cathy's family, including dental records.
The circumstances behind Cathy's death and her connection to being found in San Mateo County are under investigation, according to the San Mateo County Sheriff's Office.