MESQUITE, Texas (KXAN) — The family of a teenager who died in the custody of a Texas police department tells KXAN it plans to proceed with a lawsuit against the officer who shocked their son multiple times the night of his death.

Kathy and Robert Dyer’s suit claims Mesquite police officers used excessive force during the August 2013 arrest of their 18-year-old son, Graham, who was high on LSD. During transport to jail, Graham slammed his head more than 50 times against a metal barrier in the back of the police cruiser. The teen later died in the hospital from self-inflicted head injuries, according to a medical examiner’s report.

“There was no reason for him to die,” Kathy Dyer told KXAN. “What happened to serve and protect? What happened to we’re here to help this young man that’s in distress?”

This month, U.S. District Judge Jane Boyle ruled a portion of the family’s original suit could proceed – the excessive force claim against Officer Alan Gafford, who shocked Graham “in multiple locations of his body, including his testicles.”

In the federal order, Gafford refutes that claim, saying he only used the stun gun on Graham on the inner thigh. But Boyle writes video of the incident is evidence that the officer “used objectively unreasonable force on Graham” and that “would permit a reasonable jury to find that Graham was not resisting arrest.”

Mesquite police refused to release video of the incident to Graham’s parents. But years later, they found a backdoor way to obtain the footage through the FBI. It showed the police cruiser pulling over when Graham continued hitting his head. Officers held him down while repeatedly shocking him with their stun guns. They can be heard telling him to “chill out” and “calm down.” One officer punches him and says, “I’m going to kill you.”

The judge dismissed other claims against Mesquite police in the lawsuit. City officials have declined interview requests made by KXAN.

In 2017, the Dyers testified before state lawmakers in favor of a bill to close a loophole in the Texas Public Information Act that allowed police to withhold video and other records in the case. The law gives police discretion to deny public information requests in closed cases that do not go through the court process, including cases when a suspect dies while in custody.

This issue was featured in KXAN’s investigative series, DENIED, this year, highlighting the widespread use of the loophole amid questions of police transparency and possible wrongdoing.

“We were told we couldn’t bring any kind of civil action because we didn’t have sufficient evidence,” Kathy Dyer explained to the House panel, which unanimously approved the measure. However, the bill stalled before reaching the House floor for a vote.

The bill’s author, Rep. Joe Moody, D-El Paso, who is up for re-election this year, tells KXAN, “if I return to the legislature, I will file that bill again.” The next legislative session begins in January.