Eric Sweeney, who was living with his brother at the time, told police that he had taken a shower and gone downstairs to his basement bedroom when "he heard something break" and a "deep, male voice yelling followed by multiple 'pops.'"
The New Hampshire teenager charged with murdering his brother's wife and their two young children told police that the three were killed by a home intruder, according to prosecutors.
A grand jury indicted Eric Sweeney on three counts of first-degree murder last month, choosing to charge the teen as an adult despite the fact that he was only 16 when he allegedly committed those crimes.
Details about what cops say happened that day are now finally being revealed in a motion for order of no bail filed by prosecutors and obtained by Inside Edition Digital.
Eric, who had been living with his older brother at the time of the murders, told police that he had taken a shower and gone downstairs to his basement bedroom when "he heard something break" and a "deep, male voice yelling followed by multiple 'pops,'" according to the motion.
He then told police that he waited a while before going upstairs, grabbed his sister-in-law's phone and keys, exited the residence, and drove off in a truck, according to the motion.
At no point did he check on the well-being of his sister-in-law Kassandra, 25, or his two young nephews, 4-year-old Benjamin and 23-month-old Mason, according to the motion.
Eric told police that he "believed they were injured," but did not call 911 or ask for help despite there being a large group of tree workers on his block that day.
Instead, Eric called his brother Sean, who had to place the 911 call himself, according to the motion, telling the dispatcher: "I don't know ... my brother told me someone broke in and killed them all."
Prosecutors say in their motion that Eric then returned to the scene at the same time his brother arrived home.
Police then sat down with Sean, who revealed he had two guns in the home, one of which was missing from the safe. That gun was recovered a week later on the side of the road and determined to be the weapon that fired the casings found near the bodies of the three victims, according to the affidavit.
There had already been issues with Eric as well prior to the shooting, Sean told police.
"Sean told officers that there was growing tension in the family because of the defendant's behaviors to the point that the defendant would not listen to him and they were barely speaking to one another," the motion says. "He stated that he had installed a lock on the door to the master bedroom, in order to keep the defendant out of the room but that he didn’t believe that Kassandra locked the door, Sean told investigators that he and Kassandra wanted the defendant out of their home and had been taking steps to remove him."
Eric's claims of a home invasion were quickly debunked thanks to footage from a Ring camera and interviews with the tree workers who had been on the street that day, with both showing no one else entered the house that morning, according to the motion.
Prosecutors allege that it was Eric who killed the three, and in their motion share the heartbreaking final exchange between Kassandra and Sean.
Minutes before she was shot dead, Kassandra sent Sean photos and videos of their two sons and wrote: "I hope they make you laugh."
Eric has yet to enter a plea to the grand jury charges and his lawyer did not respond to a request for comment.
