Remember the officers’ appreciation of Rory Vertigan’s actions the next time you hear some anti-gunner saying, “The cops don’t want private citizens to carry guns.”

Four teenagers have been charged in connection with the incident early Sunday morning along an isolated dirt road in Mont Vernon, a town of about 2,000.

In a news release Tuesday, the New Hampshire Department of Justice identified the victim as 42-year-old Kimberly Cates. The medical examiner determined that she died from “multiple sharp injuries to the head, torso, left arm, and left leg.”

The victim’s 10-year-old daughter sustained serious knife injuries that required hours of surgery.

The men, the authorities say, had already strangled Dr. Petit’s wife, Jennifer Hawke-Petit, 48, and in short order would also kill the couple’s two daughters, Hayley, 17, and Michaela, 11. The elder suspect, Steven J. Hayes, 44, had poured gasoline on the girls and their mother, according to a lawyer and a law enforcement official involved in the case, in hopes of concealing DNA evidence of sexual assault. He had raped Ms. Hawke-Petit, and his partner, Joshua Komisarjevsky, 26, had sexually assaulted Michaela.

Moments after Dr. Petit escaped, as the house was being surrounded by police officers, the men lighted the gasoline. The girls were tied to their beds but alive when the gas Mr. Hayes had spread around the house was set aflame.