The man who shot and killed two auxiliary police officers and a waiter before being killed on Wednesday night was an ex-Marine likely bent on avenging the firing of a friend, police officials said.

David Garvin, 42, shot 15 rounds into the back of Alfredo Romero Morales, 33, at a Greenwich Village pizzeria, before taking the lives of Yevgeniy Marshalik, 19, and Nicholas Pekearo, 28, who were unarmed volunteers on patrol.

Garvin was a regular at DeMarco’s, on the corner of Houston and MacDougal streets, but when a friend who worked as a chef was fired last month, he apparently began plotting revenge, the police commissioner, Raymond Kelly, said at a press conference.

Police are also investigating whether Garvin was mentally unstable, he said.

“A family member indicated that Garvin had exhibited increasing paranoia in recent years, claiming that people were out to get him,” Mr. Kelly said.

Garvin served in the United States Marine Corps between 1986 and 1988, when he was less than honorably discharged from the service for unsatisfactory performance, Mr. Kelly, who is himself a retired Marine colonel, said.

Garvin moved to New York City two years ago from his native Missouri, and worked as a bartender at the Raccoon Lodge on Warren Street in downtown Manhattan, where he was fired about three weeks ago, Mr. Kelly said.

“He seemed like a regular guy, except he couldn’t control himself with drinking while working,” the owner of the Raccoon Lodge, Andreas Nowara, said.

The co-owner of DeMarco’s, Margaret Mieles, said Romero sometimes was charged with the task of telling unruly customers to leave the restaurant. Mr. Kelly said Garvin was ejected from the restaurant at least once.

An employee at DeMarco’s who witnessed the murder, Jose Louis Gomez, said that Romero never had any problems with Garvin when Garvin ate at the restaurant on Sundays. The meal was always a bowl of pasta, Ms. Mieles said.

At around 9:20 p.m. Wednesday, Garvin entered the restaurant wearing a fake beard and a Yankees cap. He took a seat at the bar. Unbeknownst to Romero he was equipped with a 9 mm handgun hidden in a hip holster and a semiautomatic weapon in a black backpack, along with nearly 100 rounds of ammunition, Mr. Kelly said.

Romero, who witnesses said appeared nervous, handed Garvin a menu, Mr. Kelly said. When Romero turned from Garvin, Garvin unloaded 15 rounds into his back.

Garvin then walked out of DeMarco’s and headed north on MacDougal Street, before turning right onto Bleecker Street, Mr. Kelly said.
The two auxiliary officers confronted Garvin as he approached the corner of Bleecker and Sullivan streets, ordering him to drop his bag, Mr. Kelly said.

Garvin proceeded to punch one of the officers, likely Pekearo, and then ran north on Sullivan Street, Mr. Kelly said.

The officers chased Garvin up the opposite side of Sullivan Street. Garvin then abruptly stopped, and turned back in the direction of the officers, Mr. Kelly said. It was likely that Garvin had just reloaded his weapon, Mr. Kelly said.

Crossing the street towards Pekearo, Garvin fired six shots, one of which struck Pekearo in the head at close range, killing him. Garvin then sprinted after Marshalik, who had crossed the street and taken cover behind a parked car. In what Mr. Kelly described as an “execution-style” shooting, Garvin fired one round into the head of the officer. The fatal encounter with the officers was caught on surveillance footage, which Mr. Kelly showed yesterday.

By then, non-auxiliary police officers had arrived on the scene, and chased Garvin south on Sullivan Street, exchanging volleys of gunfire.
Garvin doubled back onto Bleecker Street, and entered the Village Tannery with his gun raised, witnesses told investigators. Garvin then abruptly emerged from store, where police yelled, “Police. Don’t Move. Drop your weapon,” Mr. Kelly said.

When Garvin refused, police fired multiple shots at the suspect, Mr. Kelly said. He had about 30 gunshot wounds, but those included entry and exit holes. He was hit in the chest, throat, back, and knee, an eyewitness, and owner of the store adjacent to the Village Tannery, Harbir Singh, said.

“The guy took like 30 bullets, and was still standing and swaying,” Mr. Singh said.

At yesterday’s press conference Mr. Kelly applauded the bravery of the two fallen officers.

“The fact that more lives were not lost is due in no small measure to auxiliary officers Pekearo and Marshalik,” Mr. Kelly said.