ST. LOUIS -- A St. Louis police officer who pleaded guilty to accidentally killing a female colleague while playing a variation of Russian roulette said the woman knew the risk she was taking.

Nathaniel Hendren made the response Wednesday in a wrongful death lawsuit filed on behalf of the mother of Katlyn Alix, 24, who also was a St. Louis officer, KSDK reported. Hendren is serving a seven-year sentence for involuntary manslaughter for killing Alix at his home in January 2019 while he was supposed to be on duty elsewhere.

Also named in the lawsuit is Hendren's partner on the force, who also was at the home while on duty. Alix was off-duty at the time.

In the response, Hendren admitted to acting recklessly on the night of Alix's death. But his attorney, Talmage Newton, said Alix assumed risk by voluntarily participating in the game.

Hendren also said he and Alix were involved in a romantic relationship, and Alix had been planning to divorce her husband. Hendren said Alix was moving in with him when she was shot.

When Alix and officer Patrick Riordan got to his house, Hendren admitted he drank a small amount of alcohol. He said Alix also drank alcohol. He denied any illegal drug use by the three of them.

Hendren admitted taking out his personal revolver, but he claimed Alix was the first person to brandish an off-duty weapon that night. The response said he did not believe the cartridge was in the "active cylinder position" when he pointed the gun at Alix and pulled the trigger.

"Defendant states that Alix voluntarily engaged in this activity and assumed the risk of bodily injury or death," Talmage said in the response.

Hendren denied he had a history of forcing previous girlfriends to play Russian roulette. He also disputed having substance abuse and psychiatric issues, including post-traumatic stress disorder.

Hendren, who left the police department soon after the shooting, previously apologized when he was sentenced, telling Alix's mother he hoped his plea could "help heal the brokenness I've caused."