Police have released new details about a police-involved shooting in Rotterdam that left one man dead. Police held a news conference Wednesday morning, and TWC News' Geoff Redick was there.

ROTTERDAM, N.Y. — Law enforcement officials said Wednesday that the first police-involved shooting in their town's memory was justified, because the slain 30-year-old suspect did not heed commands to drop his weapons and surrender.

William J. Clark III was shot in the head and chest by a Rotterdam patrol officer Sunday. At a Wednesday morning news conference, police confirmed Clark was a veteran of the U.S. Marine Corps and was known to suffer from undisclosed mental health issues. State Police Major William Keeler said that, during an independent investigation, Clark's mother mentioned that he had not taken prescribed medication for his mental troubles.

"The investigation is 99.9 percent wrapped up," Keeler said. "It is our determination that the shooting was, in fact, justified."

Keeler said the final portion of the investigation is determining what medications Clark was neglecting at the time of the shooting.

Releasing an expanded timeline of events Wednesday, State Police explained that Clark's mother first called police Sunday, reporting that her son was walking around their Roberta Road home and swinging serrated kitchen knives. When two Rotterdam Police officers arrived on scene, Clark hid behind a bedroom door. Police found him after a 10-minute search.

"The officers actually pleaded with him: 'Put down the knives; let us help you,' " said Keeler. The major also explained that a sergeant tried to deploy a Taser against Clark, but the electrified prongs did not make contact.

According to police, Clark then stabbed the sergeant in his bulletproof vest before slashing the second officer on the back of his head. The injured officer then shot at Clark four times with his service pistol, hitting Clark three times. A fourth bullet lodged in the wall.

"It happened so quickly," said Keeler. A Rotterdam police spokesman estimated the violent portion of the encounter lasted four seconds. Clark was later pronounced dead at the scene.

"[The officers] are under no obligation to retreat, and they did what they were trained to do," Keeler explained.

Asked why officers did not treat Sunday's response as an armed stand-off and surround the house instead, Rotterdam Chief James Hamilton cited the nature of the call. 

"Each case is different," he said. "In this case, we had the obligation to go and conduct an investigation, to determine if [Clark] was a threat to himself or others."

Other than Clark's mother, who made the 911 call, no one was home during the incident.

Rotterdam Police said Wednesday that all of their officers have taken a 16-hour training course within the last year, directed at dealing with individuals under extreme emotional duress — including PTSD. The training was sponsored by the New York Justice Center for the Protection of People with Special Needs.

A representative for the United States Marine Corps confirmed Wednesday evening that Clark served five years as a rifleman with the Marines, including a seven-month tour in Iraq in 2009. He separated from the USMC in May of 2013. Clark was awarded four medals: the Armed Forces Reserve Medal, Iraq Campaign Medal, Global War on Terrorism Service Medal and the National Defense Service Medal.

Police said Wednesday that Clark has been known to area law enforcement for several years, due to prior interactions with police. A FOIL request for Clark's police report history with one area department had not been completed by deadline.