HAVERHILL, N.H. – Former honors student and student council president Robert Tulloch spurned his attorney’s advice Thursday and admitted savagely killing two Dartmouth College professors with his best friend last year.

The Vermont teen-ager, who abruptly dropped his planned insanity defense this week, thus ended a case that captured national attention for its brutality and senselessness.

Judge Peter Smith gave Tulloch, 18, the mandatory sentence for first-degree murder, life in prison without parole.

His partner, James Parker, 17, turned state’s evidence in an earlier plea agreement. He received his negotiated sentence of 25 years to life in prison a few hours later in Grafton County Superior Court.

Parker, who admitted being an accomplice to one murder, had agreed to testify against Tulloch. He broke down at his brief hearing and had trouble getting up to speak.

“I’m sorry,” he said, crying. “There’s not much more I can say than that. I’m just really sorry.”

At Tulloch’s hearing, prosecutor Kelly Ayotte said Tulloch instigated the crime and dominated the partnership of the once inseparable friends from tiny Chelsea, Vt.

Until Tulloch suddenly grabbed a knife and began stabbing Dartmouth professor Half Zantop in his Hanover home on Jan. 27, 2001, Ayotte said, Parker believed he was on just another dry run of the pair’s harebrained scheme to steal ATM cards for cash to move to Australia.

She acknowledged, however, that Parker, at Tulloch’s direction, cut Susanne Zantop’s throat when her husband’s screams brought her running from her kitchen.

Tulloch was calm and matter-of-fact during his hearing. But friend Russ Kellogg, who visited Tulloch frequently in jail, said Tulloch is sorry.

“Robert wants it to be known that it is untrue that he had no remorse,” Kellogg said.

“He’s not angry with Jim [Parker],” he added. “There is no bitterness.”

Ayotte said the slaughter had its genesis two years earlier when the two bored teen-agers began thinking up ways to collect $10,000 to move to Australia. She said they slowly graduated from stealing mail to murder, with Tulloch upping the ante as successive schemes failed or proved tedious.

She said they quickly gave up legal ideas for raising money and talked about stealing cars. They stole an all-terrain vehicle, but couldn’t sell it because they didn’t have the title.

They stole mail, hoping to find money or credit cards, before Tulloch decided that “jumping people” would produce better results, Ayotte said.

She said they ordered stun guns on the Internet, but Tulloch’s mother intercepted them. Tulloch then suggested talking their way into homes and demanding ATM cards and personal identification numbers, or PINs, at knifepoint before killing the victims, she said.

“Tulloch discussed with Parker that they would have to be able to kill people so that they could be sort of ‘bad asses’ when they went to Australia,” she added.

Their first attempt was in Vershire, Vt., near Chelsea, six months before the murders, Ayotte said. Dressed in black and using old Army knives, they dug a grave outside for the bodies, which they planned to wrap in plastic, she said.

They fled when the homeowner answered the door holding a gun.

The other failures were the same month as the murders, including one the same day at a neighbor’s home. No one was home.

As they approached the Zantops’ contemporary home, Ayotte said Parker wore a backpack containing foot-long commando knives he recently had bought over the Internet, duct tape, zip ties and notebooks.

They told Half Zantop, who answered the door, they were students conducting an environmental survey. Zantop, 62, gave them seats in his study, where Parker took notes while Tulloch asked questions.

“When their interview was done, Parker thought they were going to leave, like in their other attempts,” Ayotte said.

But then Zantop offered to give the boys the name of a friend who could help with their study. As he dug into his wallet to find the friend’s business card, the boys noticed a thick fold of cash. Tulloch reached into the pack and grabbed a knife, Ayotte said.

She said Tulloch lunged at Zantop, stabbing him repeatedly in the chest and slashing his face. She said Parker grabbed Susanne Zantop, 55, as she rushed into the study in response to her husband’s screams.

At Tulloch’s direction, Parker used the other knife to cut her throat, Ayotte said. She said Tulloch then cut Half Zantop’s throat.

The pair fled with Half Zantop’s wallet, which had what they believed were PINs. But they decided that using them would be too risky.

Wiping blood off their hands in snow at the side of an interstate, they changed clothes at Tulloch’s home, then headed for a Barnes & Noble bookstore, where Ayotte said they read about how soldiers cope with killing.

They later drove back to Hanover to retrieve the knife sheaths, but found a police car in the driveway. Later, hearing nothing about the sheaths on the news, they foolishly concluded the police didn’t know about them.

After the murders, the two spent a sleepless night at Tulloch’s house, thinking every passing car was the police. They talked about jumping out a window to escape, and Tulloch raised the possibility of killing a police officer if necessary, Ayotte said.

The sheaths, purchased with the knives, led police to Chelsea three weeks later. The pair voluntarily gave their fingerprints, then fled. They were captured at an Indiana truck stop four days later.

Tulloch told friends he decided to plead guilty because of the strength of the state’s case and his desire to spare his family the pain of a trial. His lawyer opposed the move.

Susanne Zantop was head of Dartmouth’s German studies department; her husband taught Earth sciences. Respected in their fields, the German-born professors were beloved by colleagues and students, many of whom had an open invitation to their home a few miles from the Dartmouth campus.

With her sister standing beside her, one of the couple’s two adult daughters spoke before Tulloch’s sentencing.

“There’s no statement in the entire world that can capture the absolute horror, disbelief, pain, sadness and anger that my sister, my family and friends have experienced since the murders,” said Veronika Zantop, a doctor who lives in the Seattle area.

“Rather than focus on the inhumanity and monstrosity and the sheer stupidity of their brutal and senseless deaths, I try to console myself by trying to perpetuate the essence of my parents.”