Tyngsborough Resident Charged with Murder Following Recovery of Human Remains Concealed Beneath Garage Floor

Shawn Sullivan was arrested after human remains were found buried under his garage floor. Authorities believe the remains belong to missing woman Jill Kloppenburg.

By: AXL Media

Published: Mar 17, 2026, 5:02 AM EDT

Source: Information for this report was sourced from PEOPLE

Breakthrough in Year Long Missing Person Case

A grueling fourteen month investigation into the disappearance of Jill Kloppenburg reached a grim turning point this week in Middlesex County. Massachusetts authorities announced the arrest of 40 year old Shawn Sullivan on Monday, following the discovery of human remains at his Tyngsborough property. Kloppenburg, who was 47 at the time she was last seen, vanished from her Lowell home on January 2, 2025. While the medical examiner has yet to provide a formal identification, the recovery follows specific intelligence that suggested the missing woman had met a violent end shortly after her disappearance.

Informant Leads Police to Residential Burial Site

The investigation accelerated on March 10 when a man contacted the Nashua Police Department in New Hampshire. The individual, identifying himself as a friend of Sullivan, alleged that the suspect had confessed to killing a woman named Jill. According to the informant, Sullivan admitted to shooting the victim at his home in early 2025 and subsequently burying her body beneath the floor of his garage. Nashua officers coordinated with Massachusetts authorities, who confirmed that Kloppenburg had been reported missing in February 2025 and had not had any cell phone activity since mid January of that year.

Radar Detection and Forensic Recovery

Armed with this new information, detectives from the Tyngsborough and Tewksbury Police Departments, along with State Police, executed a search warrant on March 15. Investigators focused on a large, patched area within the garage that appeared inconsistent with the rest of the flooring. Utilizing ground penetrating radar, the team confirmed an anomaly beneath the surface. Upon cutting through the patch, forensic teams recovered a plastic bag containing human remains. The Medical Examiner’s Office has confirmed the remains are human, though the victim is officially being referred to as Jane Doe pending DNA verification.