NORTHFIELD, NH – A teenager from New Hampshire plans to plead guilty to the killings of his sister-in-law and her two young sons, closing a case that shocked the local community nearly two years ago.
Eric Sweeney, 19, intends to admit to three counts of second-degree murder and one count of falsifying physical evidence in connection with the deaths of Kassandra Sweeney, 25, and her sons, Benjamin, 4, and Mason, who was just weeks away from his second birthday. The plea is expected to take place at a court hearing scheduled for Friday, according to newly filed court documents.
The tragic incident unfolded on August 3, 2022, at the Sweeney family’s Northfield residence, located about 20 miles north of Concord. Prosecutors say the events leading up to the killings were marked by rising tensions within the household, where Eric, his brother Sean Sweeney—who was also his legal guardian—and Kassandra lived with the two boys.
According to court records, conflict simmered as Eric Sweeney reportedly disregarded house rules, taking food and using tools without permission. Authorities say he also constructed makeshift weapons, which contributed to a deteriorating relationship with his brother and sister-in-law in the weeks preceding the killings.
Police logs reveal that Sean Sweeney expressed growing concern for his family’s safety in the days before the attack, citing the discovery of weapons in the garage and nearby woods. Calls to police in both June and July 2022 highlighted unrest in the home, though no arrests resulted from those calls.
On the morning of the homicides, Sean Sweeney left for work, leaving his wife, children, and brother at home. Kassandra Sweeney was with her sons, even filming them as they played, according to prosecutors. The children were later found in the same clothing they wore in those videos.
Eric Sweeney claimed he was upstairs when he heard noises coming from downstairs. He told investigators he discovered the bodies after going to check and initially called his brother before dialing 911. Authorities said Sweeney reported a home invasion and denied involvement.
However, scrutiny quickly focused on the teenager. Family members, including his father, voiced suspicion about Eric’s involvement to investigators. Forensic evidence further implicated him, as gunshot residue was discovered on his hands.
In the aftermath, authorities charged Eric Sweeney with three counts of first-degree murder, though court records indicate he now plans to plead guilty to lesser charges. The evidence-tampering charge stems from his alleged destruction or disposal of the .40-caliber handgun used in the crimes.
Eric Sweeney’s arrest followed eight days after the killings, although his name was initially withheld due to his age at the time of the offense, just over 16 years old. Authorities described the family’s devastation in the wake of the tragedy, noting Sean Sweeney’s cooperation with investigators.
The community responded with an outpouring of support, including a fundraising campaign that raised over $50,000 for the family’s immediate needs and memorial expenses. Relatives remembered Kassandra Sweeney as a kind and caring mother and described Benjamin and Mason as two joyful young children.
Sweeney’s guilty plea is expected to bring a measure of closure to a community still reeling from the loss caused by the murders. Sentencing will take place following the entry of his plea.