CONCORD, N.H. (AP) — A young man from New Hampshire who was 16 when he killed his sister-in-law and two young nephews deserves at least 97 years in prison, prosecutors will tell a judge Friday.

Eric Sweeney, now 19, had been living with his older brother’s family in Northfield for three years when he fatally shot Kassandra Sweeney, 25, and her sons, 4-year-old Benjamin and 23-month-old Mason, in August 2022.

Originally charged with first-degree murder, Sweeney instead pleaded guilty in August to lesser second-degree murder charges. At a sentencing hearing Friday, defense lawyers will seek a prison term of 40 years to life, based in part on the “immeasurable trauma” Sweeney suffered as a child, including a mother who “dragged him through drug dens and a succession of abusive father figures.”

“We are asking the court to grant Eric some measure of mercy,” attorneys Lauren Prusiner and Morgan Taggart-Hampton wrote in a sentencing memorandum made public Thursday.

Prosecutors are seeking consecutive sentences of 35 years to life for Kassandra Sweeney’s death and 40 years to life for each of the boys’ deaths, with up to 18 years suspended if goals related to education, mental health treatment and good behavior are met.

“Benjamin and Mason embody the reason why crimes against children deserve the harshest of penal sanctions. They did absolutely nothing wrong, they were innocent and utterly blameless for what the defendant did,” Assistant Attorney General Bethany Durand wrote in her sentencing memo. “Their murders deserve separate, consecutive sentences.”

Kassandra Sweeney, a nursing assistant, worked nights so she could care for her boys during the day. On the morning of the killings, she had fixed them a snack and was recording videos of them playing and laughing to send to her husband. Four minutes after she sent the last video, all three were shot in the head, Benjamin through the hood of the dinosaur costume he was wearing.

Sweeney later told police he was in the basement when he heard something break upstairs, a man with a deep voice yelling and multiple “pops,” according to court documents. He said he went upstairs and found his sister-in-law and nephews on the floor bleeding and then took Kassandra’s cellphone and keys and drove away. He then called his brother, who called police.

According to prosecutors, Sweeney’s older brother, Sean, and his wife were serving as the teen’s guardians when Sweeney’s “increasing behavioral issues” including lying and violating house rules began causing tensions in the home.

Without providing a motive for the killings, his defense lawyers wrote that, “His depression deepened. He knew he was on the brink of losing the safest, most moving home he had ever known.”

They argue Sweeney’s behaviors stemmed from his deeply traumatic childhood.

“He stood on the street at six years old asking bystanders to buy him food,” the attorneys wrote. “He wore shoes with the soles coming apart, and worried that any toys he received for Christmas through Toys for Tots would be sold for drug money.”

The defense argues that sentencing Sweeney to what would effectively be a life sentence without parole violates the state Constitution. They said he loved those he killed and will “grapple with the consequences of his actions for the rest of his days.”

“A forty year minimum sentence would offer Eric hope that someday, he can make a meaningful life outside prison walls, and achieve some measure of redemption for his crimes,” they wrote.