The shocking details of how two bored teenagers butchered husband-and-wife Dartmouth College professors in their home in a plot to steal their ATM cards spilled out in court Thursday as the case ended with both youths sentenced to long prison terms.

Robert Tulloch, an 18-year-old former high school honor student, dropped his insanity defense, pleaded guilty to murder, and received the mandatory sentence of life without parole in the stabbing deaths of Half and Susanne Zantop.

His best friend, 17-year-old James Parker, was sentenced later in the day to 25 years to life as an accomplice to murder, bringing an end to a case shocking in its savagery and senselessness. Parker had struck a plea bargain in December and agreed to testify against Tulloch.

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

Tulloch calmly gave mostly yes-and-no answers to the judge’s questions and offered no explanation or apology.

At the hearing for Tulloch, prosecutor Kelly Ayotte described how the two teenagers went from stealing mail to committing murder as part of a scheme to make a lot of money and run off to Australia. She recounted how they made abortive attempts at four other houses before they talked their way into the professors’ Hanover home on Jan. 27, 2001, by posing as students taking an environmental survey.

The teenagers were packing foot-long commando knives bought over the Internet and duct tape, according to the prosecutor.

Zantop led the boys into his study, gave them each a chair and sat down at his desk. The professor answered Tulloch’s questions for 10 minutes while Parker took notes. When the interview was done, Parker thought they were going to leave and abort the plan, according to the prosecutor.

But Zantop told them they should be better prepared for the next survey and said he had a friend who could help them with research.

When Zantop opened his wallet to give the boys the friend’s business card, a wad of cash poked out, and Tulloch abruptly reached into a backpack, grabbed one of the knives and lunged at Zantop, stabbing him repeatedly in the chest, Ayotte said.

Susanne Zantop came running when she heard her husband’s screams. At Tulloch’s direction, Parker slit her throat, Ayotte said. Tulloch then stabbed the woman all over.

“It was a brutal attack. There was a terrible struggle there,” the prosecutor said.

The pair fled with Zantop’s wallet, which had what they believed were PIN numbers for ATM cards. But they decided that using them would be too risky.

They were ultimately traced to the crime weeks later by way of the commando knife sheaths they had mistakenly left behind. They were captured at a truck stop in Indiana.

In the months after the attacks, townspeople and the news media offered a host of exotic theories about the slayings — a thrill-killing, revenge for some kind of slight, even neo-Nazi hatred of the Zantops for speaking out against the Holocaust in their native Germany. But ultimately prosecutors said it was a robbery, with the victims picked at random.

Susanne Zantop, 55, was head of Dartmouth’s German studies department. Her husband, 62, taught Earth sciences.

–Associated Press