An accused murderer has been arrested after he helped lead cops to a body buried under his Massachusetts garage — assumed to be a female friend who went missing more than a year ago, officials said.

Shawn Sullivan, 40, was eyed after allegedly confessing to a friend that he shot and buried a woman named “Jill” around January 2025 — the same time Jill Kloppenburg was last seen alive, Middlesex County District Attorney Marian Ryan told reporters Monday.

Police used ground-penetrating radar that found something buried beneath a “large patched area” in the two-car garage of Sullivan’s family’s home in Tyngsborough, about 28 miles north of Boston, the DA’s Office said.

After breaking ground, they discovered human remains in a plastic bag.

Although they have not been formally identified as Kloppenburg, police said they hoped the discovery would bring closure to her family, and an uncle said investigators are “100% positive” it is her.

Sullivan was charged with murder, assault and battery with a dangerous weapon causing serious bodily injury, and improper disposal of a body.

He was friends with the 47-year-old missing woman, who “had been in his home and … had allegedly been with her around the time of her disappearance,” the DA said.

Kloppenburg was last seen leaving her home in Lowell, Mass., on Jan. 2, 2025, and has not been seen or heard from since. She was reported missing to Tewksbury police in February 2025, according to the FBI’s missing persons database.

Before she was reported missing, Kloppenburg’s friends had not physically seen her since August 2024 or spoken over the phone since November 2024, according to Ryan. Her last known activity on her phone was Jan. 14, 2025.

A longtime friend who has been desperately trying to find Kloppenburg was horrififed to learn of her apparent ending.

“You don’t throw her away,” Ann Matlosz told Boston 25 of the alleged killer. “You don’t throw anybody away. They don’t deserve that … Like why? Like how little of a man are you?”

Kloppenburg’s uncle, Steven Kloppenburg, posted on Facebook that he was told investigators “were 100% positive the remains were hers though they still have to confirm it with DNA and an autopsy…”

“She’s been missing for 14 months and has probably been out there for the whole time,” he wrote, according to CBS News.

Kloppenburg’s family told the outlet they can “now focus on justice and healing.”