WATCH: Florida School in Antigay Bullying Investigation

Zephyrhills High School in Florida, which saw a student try to take his own life because of antigay bullying a year ago, is under investigation by the U.S. Department of Education.

The department's Office of Civil Rights is investigating based on a complaint by the mother of Zachery Gray that he and other students "have been subjected to harassment based on gender stereotypes," Tampa Bay-area TV station WFLA reports.

Gray is paralyzed, brain-damaged, and unable to speak after attempting suicide by hanging in May of last year, in the wake of being repeatedly called "Gay Zach, fag, queer," said his mother, Lynn "Sissy" Gray. Zach, who identifies as heterosexual, reported the harassment to a teacher, but she took no action, his mother said.

Four months before Zachery Gray's suicide attempt, another student in the same school district shot himself to death after enduring antigay bullying that included a simulated rape. Kiefer Allan, 15, attended Sunlake High School, which like Zephyrhills is part of the Pasco County district. Police recommended that the students who pinned him down and simulated the rape be charged with battery, but prosecutors dropped the case.

Florida has a law, enacted in 2008, requiring schools to take action against bullying, but the incidents in Pasco County and elsewhere have left advocates questioning if the law is working. "When it passed, that was my crowning achievement as a lawyer," said David Tirella, who worked for the law. "We had tears in our eyes." Now, he told the TV station, "I'm disillusioned. Why'd we do all that?"