Investigators recover human remains beneath Tyngsborough garage floor as Jill Kloppenburg identification efforts continue

Discovery under a garage floor prompts murder charge as identification remains pending

Authorities investigating the disappearance of Jill Kloppenburg, a Massachusetts woman last known to be in Lowell in early 2025, have recovered human remains from beneath the floor of a garage in Tyngsborough. Prosecutors have charged a Tyngsborough man with murder and related offenses while the Office of the Chief Medical Examiner works to establish the identity of the remains.

The defendant, Shawn Sullivan, 40, faces charges including murder, assault and battery with a dangerous weapon, and improper disposal of human remains. The case is being prosecuted in Middlesex County, and Sullivan was expected to be arraigned in Lowell District Court.

Timeline: Kloppenburg’s disappearance and the investigative breakthrough

Kloppenburg was last known to have contact on Jan. 2, 2025, after leaving a residence on Broadway Street in Lowell. She was later reported missing on Feb. 26, 2025, after friends and others said they had not seen or heard from her.

The investigation accelerated this month after law enforcement in New Hampshire received information on March 10 indicating Sullivan had told another person he killed a woman named “Jill” at his home during 2025. Prosecutors allege Sullivan said he shot the woman and buried her beneath the garage floor at his Tyngsborough property.

Search of Tyngsborough property and forensic recovery

When investigators went to the Tyngsborough home, they observed a patched area of the garage floor measuring roughly five feet by three feet. Ground-penetrating radar indicated something had been buried below the surface, prompting a targeted excavation.

Working with the medical examiner’s office, investigators cut through the garage floor and recovered a plastic bag containing human remains. The medical examiner confirmed the remains are human. As of the latest update, prosecutors said the remains had not yet been formally identified, and the case proceeds using a “Jane Doe” designation for the victim while identification work continues.

In cases involving recovered remains, identification may depend on factors including condition of the remains, available records, and confirmatory forensic testing.

Relationship and next steps in court

Prosecutors have stated that Kloppenburg and Sullivan were friends at the time of her disappearance. Investigators have not publicly detailed the nature of their relationship or any motive, and no cause of death has been publicly confirmed in the case filings summarized to date.

• Key pending step: formal identification of the remains by forensic methods.
• Criminal process: arraignment and subsequent hearings in Lowell District Court, with charging documents expected to outline evidence and probable cause allegations.
• Public safety: authorities continue to seek information related to Kloppenburg’s disappearance as the investigation remains active.

The outcome of the identification process is expected to determine whether prosecutors amend the case to name a specific victim and may shape additional charging decisions as the investigation develops.