Lawyers for Michael Addison had sought a life sentence, arguing that he acted recklessly, not intentionally, and suffered from an abusive childhood and possible brain damage from his mother's heavy drinking while she was pregnant.
Prosecutors emphasized Addison's record of violence, including a crime spree a week before Officer Michael Briggs was shot in the head, and noted that Addison had said he would "pop a cop" if necessary.
Addison, 28, had no reaction as the Hillsborough County Superior Court jury announced its verdict after about 13 hours of deliberation over four days. The state Supreme Court will automatically review the conviction and sentence, and the defense said it will appeal.
The judge must formally impose the sentence, but cannot change it.
New Hampshire hasn't executed anyone since 1939. The last time a New Hampshire court imposed the death penalty was in 1959, but the lives of the two convicted men were spared when the U.S. Supreme Court struck down capital punishment for a time in the 1970s. In 2004, a federal judge in Massachusetts, which has no death penalty, ordered convicted killer Gary Sampson executed in New Hampshire, but Sampson is appealing and is being held in Indiana.
Briggs' wife, two young sons and parents attended Addison's sentencing. His father, Leland Briggs, said he hopes the verdict will help protect other police officers.
"This is what we wanted. This is what we got. I love my son and I'm glad," said Briggs, a former police officer himself.
In June, Judge Kathleen McGuire rejected claims that racial prejudice would prevent Addison, who is black, from getting a fair trial in predominantly white New Hampshire. She said there was no evidence that race influenced the state to seek the death penalty.
Jurors had been screened for bias and had to certify Thursday that race had not influenced their decision.
When Briggs, 35, and his bicycle partner came across Addison and friend Antoine Bell-Rogers in an alley early on Oct. 16, 2006, they recognized the men as a suspects in a recent shooting and two armed robberies and ordered them to stop. Addison turned and shot Briggs in the head at close range, testimony showed.
The defense admitted on the first day of the trial that Addison killed Briggs, but defense attorney David Rothstein said the act was "fast," "totally unplanned" and "reckless."
Prosecutors called the shooting cold-blooded and premeditated.
"That fatal shot was no accident. It was no reckless misjudgment or panic-driven mistake," Attorney General Kelly Ayotte said in her opening statement.
The defense pointed to Addison's absentee parents and rocky childhood as grounds for mercy. Testimony showed that Addison's late mother, Cheryl Kiser, drank heavily, used drugs, and was known for violent outbursts, while his father, Michael Wilson, smoked crack throughout Addison's childhood and was rarely there for his son.
But Ayotte said sentencing Addison to life would have amounted to a free pass for Briggs' murder because Addison faced decades in prison for other convictions.
"There are millions (and) millions of people in this country who unfortunately come from far, far worse backgrounds than the defendant and they don't go out and harm and murder people," she argued, adding that it was "shameful the defendant is using his deceased mother as an excuse" for his crimes.
Addison's attorneys have said he couldn't get a fair trial in a city that revered Briggs and was outraged by his murder. The defense also cited cases of premeditated multiple murders that did not result in death sentences.
"We continue to believe that the objections we made before the trial regarding this process are valid, especially objections regarding the location of the trial and the comparison of this case to other cases," defense attorney Richard Guerriero said in a statement.
In October, a jury in Brentwood handed down the state's first capital murder conviction since 1959 in the murder-for-hire case of millionaire John Brooks, who is appealing. The jury gave Brooks, who is white, life without parole, the only alternative to the death penalty in the capital murder statute.
New Hampshire law limits the death penalty to a handful of situations including murder for hire and murder of a police officer.