A lieutenant with the nation’s largest sheriff’s department claims his supervisors retaliated against him for trying to warn the public before a killing in a popular state park outside Los Angeles, according to his lawsuit.

James Royal says he repeatedly pleaded with his superiors to warn people about a series of shootings in and around Malibu Creek State Park before Tristan Beaudette was killed by a single gunshot wound to the head last June as he slept in a tent with his young daughters.

Royal says his requests were denied, alleging his bosses told him it was the park’s problem and that the Los Angeles County Sheriff’s Department believed the shootings and Beaudette’s slaying were not connected. The string of shootings struck fear in campers and other outdoor enthusiasts.

Royal said he was stripped of his detective status, lost overtime privileges and was assigned less favorable shifts. He sued Los Angeles County, the sheriff’s department, retired Chief John Benedict and others on Friday, documents show.

The department did not immediately have a comment Monday.

Anthony Rauda is charged with killing Beaudette, 35, of Irvine as well as 10 counts of attempted murder and one count of attempted burglary. He pleaded not guilty in January, shortly after Beaudette’s family filed more than $90 million in claims against the sheriff’s department and several state agencies, alleging that they put Beaudette in danger by not warning the public about the shootings.

“Lt. Royal attempted to discharge his duty to the public and was shut down, and when the department actually got sued for failing to do the very thing he begged them to do, they turned the power of the badge against him to shut him down and control him . because they know he will soon be a witness in the civil wrongful death lawsuit,” Royal’s attorney, Matthew McNicholas, said in a news release Monday.

Royal was a detective lieutenant at the Malibu/Lost Hills Sheriff’s Station in 2017 when he learned of three shootings in the state park in 2016 and 2017, the claim says. He said he told his supervisors that the department should warn the public but that his supervisors said it was “state park’s problem.”

Four other shootings occurred in the same area, and again bosses denied Royal’s pleas to inform the public, the lawsuit said. After Beaudette’s death, others reported hearing gunfire nearby, which prompted a “public clamor.” His supervisors instructed him to tell others that the department’s “official position” was that the shootings and killing were not related.

Beginning in January, Royal was transferred to the less-coveted Santa Clarita Station — so-called “freeway therapy” that added 80 miles a day to his commute — and had his detective status removed in retaliation, the claim alleges.

He said he also faced an internal affairs investigation where he is accused of interfering with an investigation, lost overtime privileges and was assigned less favorable shifts.