Police arrested a Massachusetts man Tuesday afternoon in connection with the murder of GW student Jonathan Rizzo and two other unrelated killings.

Gary L. Sampson, 41, confessed to stabbing Rizzo to death after turning himself in to police during a failed house burglary. Police said Rizzo had stopped on the side of the road Friday night to help Sampson, according to The Boston Globe.

According to reports, Sampson tied the 19-year-old to a tree with a nylon rope and stabbed him repeatedly in the neck and chest before slitting his throat. He took the student’s car, which was later found at another death scene, and $110 in cash.

Rizzo’s body was found in woods near Abington, Mass., Tuesday after the student disappeared Friday.

Rizzo’s father, Michael Rizzo, said his son’s death should not deter people from trusting others, but should serve as a reminder to be careful when offering help.

“Jonathan believed and I believe that if we stop trying to help each other and trust each other, this world will never be the better place that we all want it to be,” he said Wednesday, according to The Boston Channel. “So in order for that to happen, we have to continue to trust and try to help people.

“I think the message here, though, is … we have to be more careful in how we do that.”

Sampson also confessed to killing Phillip McCloskey, 69, of Marshfield, Mass., and Robert Whitney, 58, of Concord, N.H., according to The Globe. McCloskey, who was in the early stages Alzheimer’s disease, was found stabbed to death and covered with leaves on Thursday in Marshfield after an apparent robbery.

Sampson waived extradition from Vermont Wednesday, to return home to Massachusetts to face charges, attorney Kevin Griffin said, according to reports.

Rizzo, who was a rising sophomore and member of the Kappa Sigma fraternity, was reported missing Saturday after failing to come home from work Friday night. Friends said he was last seen driving to pick up a pizza after his shift at The Weathervane Restaurant in Plymouth, Mass.

Police found Rizzo’s car outside Whitney’s Concord house, where the former Concord city councilor was found strangled to death.

According to reports, Sampson called police Tuesday to turn himself in after setting off a burglar alarm in a vacant house. A Vermont man had fled from a car after being carjacked at knifepoint by Sampson earlier in the day.

Sampson is also suspected in a series of bank robberies in North Carolina, where he allegedly used disguise techniques he learned by living with transvestites, Davidson County Sheriff Gerald Hege said.

Rizzo’s family informed police of Rizzo’s disappearance Saturday, after his boss called when Rizzo failed to show up for work that day. The parents had been out of town until Saturday morning.

Sophomore Paul Kennedy, a friend of Rizzo, said a group of family members and friends gathered at Rizzo’s home in Kingston, Mass., Sunday to search for him.

“Our hearts go out to this young man’s family, to all of his friends and to the members of his fraternity,” University President Stephen Joel Trachtenberg said in a written statement. “This was a young man who loved life and touched many other lives at home and in our community. Words truly cannot fully express our sense of grief and loss.”