A former U.S. Marine fighting alongside Ukrainian forces in Ukraine has been killed, his family confirmed to multiple media outlets Friday. 

Willy Joseph Cancel, 22, died Monday, his family said. He is the first U.S. citizen known to have been killed while fighting in Ukraine.

Cancel was working with a private military contracting company that sent contractors from various countries to fight in Ukraine, his mother, Rebecca Cabrera, told CNN. Cancel flew to Poland on March 12 and entered Ukraine shortly after.

"He wanted to go over because he believed in what Ukraine was fighting for, and he wanted to be a part of it to contain it there so it didn't come here, and that maybe our American soldiers wouldn't have to be involved in it," Cabrera said.

Cabrera said her son's body has not been found.

“They are trying, the men that were with him, but it was either grab his body or get killed," she said. "But we would love for him to come back to us.”

Cancel leaves behind a wife, Brittany, and 7-month-old son.

"My husband was very brave and a hero," Brittany Cancel told Fox News. "I did not expect to be a widow at 23 years old or for our son to be without a father. All I want is for him to come home, and to give him the proper burial he deserves."

Willy Cancel is originally from Orange County, New York, CNN reported. He worked at a private prison in Tennessee from May 2021 until January, said Matthew Davio, a spokesman for the private prison company CoreCivic. The Trousdale Turner Correctional Center, a medium security facility, is about an hour northeast of Nashville.

“As a correctional officer, Mr. Cancel served his state and his community by helping maintain a safe, secure environment where inmates can participate in life-changing reentry programs. We are grateful for his service and saddened by his loss,” Davio said in a statement.

While in the Marines from 2017-21, Cancel served as a rifleman and was stationed at Camp Lejeune, North Carolina. He was given a bad-conduct discharge after he was convicted of violating a lawful general order, Marine Corps spokesperson Maj. Jim Stenger said.

He had no war zone deployments, Stenger said. No other details on the bad-conduct conviction were provided.

The U.S. has not confirmed the reports about Cancel's death. On Friday, the State Department said it was aware of the reports and is “closely monitoring the situation. Due to privacy considerations, we have no further comment. We once again reiterate U.S. citizens should not travel to Ukraine due to the active armed conflict and the singling out of U.S. citizens in Ukraine by Russian government security officials, and that U.S. citizens in Ukraine should depart immediately if it is safe to do so using any commercial or other privately available ground transportation options.”