A civilian shooting instructor at Letterkenny Army Depot has pleaded guilty to involuntary manslaughter in the shooting death of a soldier at the facility.

The fatal incident occurred during firearms training on March 12.

Sean Stark, 38, admitted that he conducted “firearms training in a grossly negligent manner and with reckless disregard for human life,” according to information filed Monday in Pennsylvania federal court.

The shooting killed 18 year old PFC Krystofer Lopez.

The guilty plea places Stark’s admitted handling of the training at the center of the fatal shooting.

Official details remain limited because authorities have released little information through court documents or public statements.

U.S. Attorney Brian D. Miller called the “circumstances” of the March 12 incident “heartbreaking” for Lopez’s family.

Miller added, “I hope this prosecution brings some relief for the family while ensuring that justice is delivered.”

With authorities providing few public details, Lopez’s parents have described what investigators told them about the incident.

Carmen and Hector Lopez discussed those conversations with WGAL, the local NBC affiliate.

The parents said Stark failed to follow the required training protocols. According to their account, he was supposed to keep his pistol loaded while outside the facility and unload it after going inside.

Stark followed the outside portion of that protocol during a smoke break, the parents said.

They said he failed to complete the required unloading step when he returned inside the facility.

Investigators also described classroom video to Carmen and Hector Lopez, according to the parents.

They were told that Stark “followed the wrong protocol” by pointing a firearm at Lopez and directing Lopez to point a firearm back at him.

During that exchange, Stark shot Lopez in the chest. The account provided by the parents offers the clearest available description of how the firearms training turned fatal.

Reports published several weeks after the shooting said Lopez was wearing a bulletproof vest when he was struck.

Both authorities and the family said the bullet pierced his chest and lodged in his spine.

Early reports raised the possibility that the shooting involved a defect in the M17 pistol reportedly used during the training.

That speculation proved untrue, according to the information later reported about the incident.

The Sig Sauer P320, the civilian version of the service weapon, has faced dozens of lawsuits alleging that it can fire without a trigger pull.

Those allegations concern the civilian version, while the Pentagon later addressed the military pistols in an August report.

According to that Pentagon report, there “has never been a mechanically caused accidental discharge” involving either the full size M17 or the compact M18. The finding rejected a mechanical explanation for an accidental discharge involving those military models.

War Department press materials from 2024 identified Stark as a police officer as well as a firearms and active shooter instructor.

He worked for the Directorate of Emergency Services, or DES, Law Enforcement at Letterkenny.

The Justice Department said Stark could receive up to eight years in federal prison. His potential sentence also includes supervised release and fines following the involuntary manslaughter plea.