A 21-year-old man suspected of killing his parents, his girlfriend and two members of her family has confessed to committing the grisly Louisiana rampage with a gun stolen from one of the victims -- his father, police said Tuesday.
During a joint news conference Tuesday in Louisiana, Livingston Parish Sheriff Jason Ard and Ascension Parish Sheriff Bobby Webre said Theriot will face five counts of first-degree murder once he is returned to Louisiana.
"We know what happened here," Webre said. "He killed five people. So this is a monster."
The killings unfolded around 8 a.m. on Saturday, at the Livingston Parish home of his girlfriend, Summer Ernest, 21, police said.
Ard said autopsies determined that Ernest, her 18-year-old brother Tanner Ernest and their 44-year-old father Billy Ernest were all shot once in the head.
Two children, ages 7 and 1, were at the Ernest home when the killings occurred but were spared, according to Sheriff Ard. After Theriot fled, the children went to the home of a neighbor who called the police.
"By the time the neighbors were calling 911, the incident in Ascension Parish was already happening," Ard said.
Theriot told investigators that after committing the killings in Livingston Parish, he drove 25 miles to the home of his parents, Keith and Elizabeth Theriot, both 51, and shot them both, police said.
A gravely wounded Keith Theriot managed to call police after his son left him for dead, Webre said.
"The dad still had enough life left in him to call 911 and our dispatchers did a great job relaying that information," Webre said.
When deputies arrived at his home, Keith Theriot identified the shooter as his son before he died, Webre said.
While investigators now know how the five homicides occurred, a motive for the slayings is still unclear, officials said.
"We don't know if we will ever have a motive exactly why this happened," Webre said.
Theriot began dating Summer Ernest around two weeks ago, about the same time he moved into her family's home after his parents kicked him out of their residence, according to Ard.
"He has confessed that the weapon we recovered, which was a handgun, was the weapon he used to kill the victims," Ard said. "He did tell us that he had gotten this weapon by stealing it from his father."
Theriot is being held without bail in Richmond County, Virginia, pending an extradition hearing on Friday.