Associated Press James Parker sheds tears yesterday during his sentence hearing in Grafton County Superior Court in Haverhill, N.H. Parker, 17, received a sentence of 25 years to life after pleading guilty to being an accomplice to second-degree murder in the deaths of Dartmouth professors Half and Susanne Zantop in their Hanover, N.H., home on Jan. 27, 2001.

HAVERHILL, N.H. - An 18-year-old former student council president reversed himself yesterday and pleaded guilty to murdering two Dartmouth College professors who were knifed to death early last year.

After a prosecutor described how two bored teens went from stealing mail to murder in their search for money and notoriety, Judge Peter Smith gave Robert Tulloch the mandatory sentence for first-degree murder: life in prison without parole.

Tulloch had previously pleaded innocent by reason of insanity.

His best friend, 17-year-old James Parker, pleaded guilty earlier to a reduced charge - accomplice to second-degree murder - and had been prepared to testify against Tulloch. Under a plea bargain, he was sentenced to 25 years to life in prison yesterday. Parker cried as he surveyed the courtroom and said, "I'm sorry."

Tulloch told friends he decided to plead guilty for reasons including the strength of the state's case and his desire to spare his family the pain of a trial.

Half Zantop, 62, and his 55-year-old wife, Suzanne, were slain in their home a few miles from the Dartmouth campus. The killings of the popular professors shocked Hanover, a college town of 9,600 on the Vermont line.

At Tulloch's hearing, prosecutor Kelly Ayotte said Tulloch proposed murdering people for their ATM cards to raise money so he and Parker could move to Australia.

The teens, bored in their hometown of Chelsea, Vt., stole an all-terrain vehicle but couldn't sell it because they didn't have the title, Ayotte said. They stole mail, hoping to find money or credit cards, before Tulloch decided that "jumping people" would produce better results, she said.

She said Tulloch decided on murder to eliminate witnesses and to enhance the boys' reputations once they got to Australia. They settled on talking their way into homes, demanding ATM cards and PIN numbers at knifepoint, and then killing the victims, she said.

Ayotte said the pair went to the Zantops' contemporary home on Jan. 27, 2001, because it looked as though the owners had money. In a backpack were foot-long commando knives recently bought over the Internet, duct tape and notebooks.

They told Half Zantop they were students conducting an environmental survey. He let them in and sat them down.

While talking to them, Zantop pulled out his wallet to give the boys the business card of a friend he thought could help with their study, the prosecutor said. That's when Tulloch grabbed a knife, stabbed Zantop repeatedly in the chest and slashed his face, she said.

She said Parker grabbed Susanne Zantop as she rushed in to help her husband. Both professors' throats were cut and the boys then fled with Half Zantop's wallet.

They changed clothes at Tulloch's home, then headed for a bookstore where they read about how soldiers cope with killing, Ayotte said. They later drove back to Hanover to retrieve the knife sheaths but found a police car in the driveway.

The sheaths, purchased along with the knives over the Internet, led police to Chelsea three weeks later. The pair voluntarily gave their fingerprints, then fled. They were captured a few days later while hitchhiking in Indiana, and the prosecutor said Tulloch remarked: "It's a house of cards. It took me 17 years to build. I can't put it back up again."

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.

One of the couple's adult daughters, Veronika Zantop, spoke before Tulloch's sentencing.

"There's no statement in the entire world that can capture the absolute horror, disappointment, pain, sadness and anger that my sister, my family and friends have experienced since the murders," she said.