But it has also drawn renewed focus on the murders of four men. Mr. Tartaglione, a retired police officer from Briarcliff Manor in Westchester County, was charged by federal prosecutors in Manhattan in December in the quadruple homicide and drug conspiracy. Mr. Tartaglione is being held without bail in federal jail in Brooklyn.

One of the people with knowledge of the matter said that the murders, which took place near a bar in Chester, a town about 30 minutes northwest of Haverstraw, resulted from a cocaine selling operation that had gone awry. One of the men, a landscaper, had been dispatched to Mexico to buy some cocaine that was then sold successfully by the operation upon his return.

But after a second trip, the man, who had been given a larger sum of money to buy a larger quantity of cocaine, returned from Mexico with neither the money nor the drugs, having apparently been robbed, the person said.

The men who had sent the landscaper to Mexico eventually concocted a scheme to lure him to the Likquid Lounge, a bar in Chester, the person said. The man believed he was going to meet someone who wanted to hire him for construction work, so he brought along two relatives and a friend, the person said. But the promise of day labor was just part of the plot to kill him, the person said, and the other three men were simply collateral damage.

Image Gerard Benderoth, a former police officer under investigation by the F.B.I., shot and killed himself on Wednesday.

It was unclear precisely what role the federal agents and police officers, as well as the prosecutors overseeing the case, believed that Mr. Benderoth had in the case, but they were investigating his involvement, the person said. And while they hoped to win his cooperation, they were prepared to arrest him if need be, the person said, though there were no sealed or unsealed charges against him.