Breitkopf

As he crossed the lawn, someone, apparently referring to Breitkopf, shouted the word "gun."

Len Levitt: Nassau County Police's Sad Accounting Len Levitt 2011

Needlessly killed was Geoffrey Breitkopf, 40, a 12-year veteran of the force.

Len Levitt: Nassau County Police's Sad Accounting Len Levitt 2011

According to an account in Newsday, Breitkopf took an assault rifle from his car and walked past several uniformed cops towards DiGeronimo's house, wearing his rifle on a sling around one shoulder, pointed downwards.

Len Levitt: Nassau County Police's Sad Accounting Len Levitt 2011

Just minutes later, Breitkopf and his partner arrived.

Len Levitt: Nassau County Police's Sad Accounting Len Levitt 2011

The sources say that Metropolitan Transit Authority officer Glenn Gentile didn't realize that Breitkopf - dressed in plain clothes and carrying a rifle - was a cop and shot him.

Len Levitt: Nassau County Police's Sad Accounting Len Levitt 2011

But away from the media's glare, sources say that Nassau police are assessing whether careless oversight of Breitkopf's unit and lax control of a violent crime scene set the stage for tragedy.

Len Levitt: Nassau County Police's Sad Accounting Len Levitt 2011

That Nassau cop allowed Gentile and his partner to handcuff the fallen Breitkopf - as cops do criminals - after Breitkopf was shot dead and sprawled on the ground.

Len Levitt: Nassau County Police's Sad Accounting Len Levitt 2011

The incident that led to Breitkopf's death began shortly after 8 PM on March 12, when Nassau police arrived at the home of Anthony DiGeronimo in Massapequa Park.

Len Levitt: Nassau County Police's Sad Accounting Len Levitt 2011

Police sources say that the Nassau department is examining why members of Breitkopf's elite heavy weapons unit - the Bureau of Special Operations - were permitted to arrive at a crime scene wearing plain clothes while failing to prominently display their police IDs.

Len Levitt: Nassau County Police's Sad Accounting Len Levitt 2011

Hearing "gun," one of the two MTA officers grabbed Breitkopf by the arm.

Len Levitt: Nassau County Police's Sad Accounting Len Levitt 2011