Massachusetts prosecutors say a Tyngsborough man will face murder and related charges after investigators dug through a patched garage floor and recovered human remains.
TYNGSBOROUGH, Mass. — Human remains found beneath the floor of a garage at a Tyngsborough home are believed to be those of Jill Kloppenburg, a 47-year-old woman missing for more than a year, and a 40-year-old man is now facing a murder case, authorities said Monday.
The discovery pushed a long-running missing-person case into a homicide prosecution and gave Kloppenburg’s family the first major break in months. Middlesex District Attorney Marian Ryan said investigators have not yet confirmed the remains through DNA testing or an autopsy, but officials believe they found Kloppenburg after a tip led police to the home of Shawn Sullivan. Sullivan is expected to face charges including murder, assault and battery with a dangerous weapon causing serious bodily injury, and improper disposal of human remains.
Ryan said the case turned on March 10, when Nashua, New Hampshire, police received a report from someone who said a friend had confessed to killing a woman named Jill. Investigators later identified that friend as Sullivan, of Tyngsborough. According to Ryan, the caller told police Sullivan said he had shot the woman and buried her under a garage floor. Detectives from Tyngsborough, Tewksbury and the Massachusetts State Police built on that information and, on Sunday, served a search warrant at Sullivan’s home on Audrey Avenue. Inside the garage, investigators found what Ryan described as a patched section of concrete measuring about 5 feet by 3 feet. They used ground-penetrating radar, cut through the floor and recovered a plastic bag containing human remains.
Authorities said the remains have not been formally identified, and the Office of the Chief Medical Examiner still must determine both identity and cause of death. Even so, Ryan said investigators believe the body is Kloppenburg’s. She said Kloppenburg and Sullivan knew each other, that Kloppenburg had been inside his home before, and that investigators believe he had been with her around the time she disappeared. Kloppenburg was reported missing in February 2025 by friends in Tewksbury. Ryan said those friends had not heard from her since November 2024, while other officials have said she was last seen in January 2025 and that her last cellphone communication was recorded on Jan. 14, 2025. The difference in those dates remains unresolved in public accounts, but prosecutors have described her disappearance as stretching back more than 14 months.
The scene on Audrey Avenue drew neighbors and construction crews as investigators worked through concrete and soil for hours. Neighbor Ella White told local television crews the digging continued into the evening after the search began, with crews stopping the excavation around midday but remaining at the property until after sunset. Another neighbor, Joseph McRell, said the accusations came as a shock. The remains were found in a two-car garage at a house in a quiet residential area, and the stark details of the search quickly spread through the community. For Kloppenburg’s relatives, the development was devastating but clarifying. Her uncle, Steven Kloppenburg, wrote on social media that the family believed the remains were hers, though he acknowledged official testing was still pending.
The criminal case is moving forward even before the victim’s identity is formally confirmed. Ryan said Sullivan is being held on a murder charge tied to a Jane Doe while forensic testing continues. He is also expected to face the additional counts prosecutors outlined Monday. Court proceedings were expected in Lowell District Court on Tuesday. Investigators have not publicly described a motive, any recovered weapon, or the evidence that may connect the alleged shooting to the burial site beyond the tip and the findings at the garage. They also have not said when Kloppenburg is believed to have been killed. The medical examiner’s work will likely be central to those questions, especially because prosecutors said the remains were buried for an extended period.
The case has also highlighted how a single outside report can reshape an investigation that had stalled for months. Kloppenburg’s disappearance had left friends and family without clear answers for more than a year. Ryan said the break came only after the caller in New Hampshire shared what he said Sullivan had told him. That account led officers across state and local agencies to revisit the disappearance with new urgency. By the time crews broke through the patched garage floor, investigators had found the physical evidence they said matched the tip. The emotional stakes were clear as family members and neighbors reacted publicly, some expressing grief and others disbelief that a missing woman’s case had ended beneath a suburban garage floor.
As of Monday, authorities said the remains were awaiting formal identification and autopsy findings, while Sullivan was expected in court Tuesday in Lowell. The next major step is forensic confirmation of the victim’s identity and a fuller account from prosecutors of how they believe Kloppenburg was killed.
Author note: Last updated March 17, 2026.