Timeline surrounding LI cop's slaying

The confrontation between a knife-wielding man and police was over by the time Officer Geoffrey J. Breitkopf arrived at the scene. Moments later, Breitkopf was mortally wounded.

Here is a timeline of how the tragic shooting unfolded Saturday night in Massapequa Park, according to Nassau police.

8:13 p.m.

Nassau police respond to a report of a "suspicious male" terrorizing Front Street just blocks from Village Hall and the Long Island Rail Road station.

The man, later identified as Anthony DiGeronimo, 21, is wearing a mask and "leather, Satanic-like garb" with chains and hooks. He has a knife in each hand and attached to his body are several more large knives. He is menacing residents and jumps on the hood of a car.

Two uniformed patrol officers from the nearby Seventh Precinct in Seaford confront the suspect as he walks east on Front Street. The officers say they feel threatened enough that they "almost used deadly force in the initial confrontation," according to Police Commissioner Lawrence Mulvey.

But DiGeronimo runs, taking refuge in a Fourth Avenue home just off the corner of Front Street, about 100 feet away.

The officers follow the suspect inside, and evacuate a man and woman from the house. They don't know right away that DiGeronimo lives in the ranch-style home, and that the couple are his parents.

DiGeronimo barricades himself inside a back bedroom.

Five to six minutes after the initial call

After briefly "taunting" the officers, DiGeronimo opens the bedroom door. With a large knife held high over his head, he "lunges" at the two officers, police said. One officer responds by firing four shots; the other fires three. DiGeronimo falls dead in the hallway.

In the next several minutes

Two MTA police officers arrive outside the home. They had been at the nearby LIRR station to check on a "stuck elevator," Nassau police said.

The uniformed MTA officers, monitoring the Nassau police radio frequency, go to the scene to offer assistance. During this time, several other Nassau police officers also converge on the home.

About 10 officers from the two departments are on the scene. "For all intents and purposes, we were just safeguarding the scene," Mulvey said of the minutes following DiGeronimo's shooting.

Eight to 13 minutes after officers shoot DiGeronimo

Two plainclothes officers with Nassau police's Bureau of Special Operations arrive. The elite unit often responds to high-priority calls to offer tactical expertise and back up patrol units.

"When cops need help on the street, this is who we call," said James Carver, the president of the slain officer's union, the Nassau Police Benevolent Association.

As one of the BSO officers parks their unmarked vehicle, the other -- Geoffrey J. Breitkopf, 40 -- approaches the home while carrying a rifle. Mulvey said Breitkopf held his long weapon at his side, possibly in a sling, and not in a ready-to-shoot position.

One of the MTA officers outside the home, identified by people familiar with the investigation as Glenn Gentile, apparently mistakes Breitkopf for a threat and fires one shot, striking Breitkopf in the right side.

The bullet bores through his heart and lungs, and exits out the left side of his body. Police also have not said whether the officer was wearing a bulletproof vest.

9:19 p.m.

Breitkopf is pronounced dead at Nassau University Medical Center in East Meadow.

The investigation

Mulvey said police are still investigating whether Breitkopf wore visible identification, and whether either he or the MTA officer verbally identified themselves before the fatal shot.

"We're not prepared to say exactly what led the officer to fire," Mulvey said, adding that interviews were still being conducted Sunday. "We would think he determined there was a danger afoot and misconstrued the circumstances."

Mulvey said discussions on whether the department needs to review its protocol for plainclothes officers and interagency communications began at the hospital where Breitkopf died Saturday night.

"These kinds of circumstances cause us to take a step back," he said.