New Hampshire man pleads guilty to the murders of his sister-in-law and two nephews committed while he was a teenager.

A 19-year-old man from New Hampshire has pleaded guilty to second-degree murder in connection with the tragic killings of his sister-in-law and her two young sons three years ago, when he was just a teenager. Eric Sweeney entered his plea on August 15, 2025, at the Merrimack County Superior Court in Concord, NH.

Sweeney was charged with the murders that took place on August 3, 2022, in Northfield. He was accused of fatally shooting 25-year-old Kassandra Sweeney and her two children, four-year-old Benjamin and one-year-old Mason, within the family’s residence. Authorities responded to a 911 call that morning, discovering the three victims, who were pronounced dead at the scene. According to autopsy reports, each victim suffered a single gunshot wound to the head, leading to their deaths being classified as homicides by New Hampshire Attorney General John M. Formella.

Following the incident, Sweeney, who was 16 at the time, was arrested approximately one week later. In October 2023, a grand jury formally indicted him on three counts of first-degree murder, which involves deliberately causing the deaths. Additionally, Sweeney faced charges for falsifying physical evidence, reportedly concerning the destruction or concealment of the .40 caliber handgun used in the killings.

Originally scheduled for trial next month, Sweeney decided to accept a plea deal, resulting in a guilty plea on the lesser charge of second-degree murder. In New Hampshire, the penalty for first-degree murder is a life sentence without the possibility of parole, while second-degree murder carries a maximum sentence of life in prison.

The dynamics within Sweeney’s family prior to the incident were troubling. At the time of the shootings, Sweeney’s older brother, Sean, and his wife were his legal guardians. Less than two weeks before the murders, Sean reported to police that Eric was making “strange statements.” Assistant Attorney General Bethany Durand highlighted that the family’s situation had degraded significantly, prompting Sean to install a lock on their master bedroom door to keep Eric out.

Moreover, just two months prior to the fatal shootings, Sweeney had taken his brother’s truck without permission and left them a note expressing feelings of alienation and distress, stating that he did not belong in the family and apologizing for his behavior.

Sweeney is set to be sentenced on October 3, when the court will determine his fate following this harrowing case that has profoundly affected the community.

With extensive reporting from Media News Source.