A murderer of two undercover detectives, Ronell Wilson, will die by lethal injection, a federal jury in Brooklyn decided last evening.

It is the first sentence of death to be imposed in federal court in New York State in more than 50 years.

Wilson was standing when the foreman meted out his sentence for the murders of James Nemorin and Rodney Andrews. Wilson did not flinch, and his face carried the same numb expression with which he has watched his two-month-long trial unfold.

“Yes,” the jury foreman said in a loud voice when a court clerk asked whether the defendant should die.

When the lengthy verdict form had been read aloud from beginning to end, the attention of those present shifted away from the condemned man and toward his younger brother, Daniel, who began to shout what seemed to be a curse word from his seat in the front row. A family member covered his mouth and deputy marshals escorted him from the courtroom.

That shout set off a volley of quick yells from others.

“You are a dead man!” Nemorin’s mother-in-law, Nicole Eduard, said.

This in turn was followed by words from the condemned man’s mother.

“Y’all the murderers now,” Cheryl Wilson said.

While juries in New York State courts have sent seven men to death row in recent years, no federal jury in New York has done the same since the federal death penalty was reinstated in 1988. Indeed, not since the early 1950s, when Ethel and Julius Rosenberg were condemned to die for espionage and a bank robber, Gerhad Puff, was condemned for shooting a federal agent, has a sentence of death come from a federal court in New York.

The crime for which Wilson is sentenced to die roiled the NYPD as has no other crime against police in recent memory.

Nemorin and Andrews, detectives for the elite Firearms Investigation Unit, sat up front in an unmarked police car when they were murdered with single bullets. Wilson sat in the backseat, having directed the two to the empty street where he shot them. He was convicted on a federal racketeering indictment last month. The penalty phase of his trial lasted two weeks, half of which was devoted to the defense’s portrayal of the circumstances of his childhood in Brooklyn and Staten Island. His mother was crack-addicted and his father largely absent. Through adolescence he behaved as a young child, with his thumb often in his mouth. According to the verdict form, the jury accepted most of the 18 mitigating factors the defense had proposed and even wrote into the sheet an additional one — that “possible peer pressure” had contributed to the murders. The jury rejected five proposed mitigating factors, finding that Wilson had not taken responsibility for his actions, nor shown remorse.

“Zero,” the foreman told the court loudly when asked how many jurors believed Wilson felt remorse.

Thus, the apology Wilson read aloud to the jury last week had little impact on the jury. The five-paragraph apology, which mentioned neither his crime nor the names of his victims, was the result of much litigation. A more substantive apology would have required Wilson to take the witness stand and be cross-examined, the judge, Nicholas Garaufis of U.S. District Court, said.

“The jury only heard an antiseptic statement saying that ‘I’m sorry’ and that’s about it,” one of Wilson’s attorneys, Ephraim Savitt, said following the sentencing.

The U.S. attorney in Brooklyn, Roslynn Mauskopf, hailed the death sentence as an opportunity for “our community to determine what is justice when two heroes, two cops, are murdered in cold blood.”

“It speaks to the appropriate punishment for Ronell Wilson,” Ms. Mauskopf said, adding, “It speaks to the sacrifice of every NYPD cop who puts his or her life on the line every single day to keep all of us safe.”

In statements, the police commissioner, Raymond Kelly, and Mayor Bloomberg did not include their reactions to the death sentence.

“I want to commend the jury for their difficult and courageous work,” Mr. Kelly said.

Mr. Bloomberg reiterated what he had said at the time of the conviction last month: that the memories of both detectives could be honored “by continuing their heroic work to keep illegal guns off our streets.”

The case against Wilson went to federal court after a 2004 decision by the New York State Court of Appeals struck down the state death penalty on a technicality. Following the decision, the office of the Staten Island district attorney handed over the case to Ms. Mauskopf for the sole purpose of seeking the death penalty.

As the prosecutors on the case, Colleen Kavanagh, Jack Smith, and Morris Fodeman, left the courtroom, dozens of police detectives clapped for them for almost a minute.

Wilson’s attorneys said they would appeal jury’s verdict. The director of the New York Civil Liberties Union pledged the organization’s support to the appeal.

Those appeals could take years, but the president of the city Detectives Endowment Association, Michael Palladino, said he remained hopeful that Wilson would be eventually be executed. He said that he initially thought that yesterday’s sentence was unlikely.