Tyngsborough Man Charged With Murder After Human Remains Discovered Beneath Patched Garage Floor Concrete

Shawn Sullivan faces murder charges after police find human remains buried under epoxy and concrete in his Tyngsborough garage during a missing person search.

By: AXL Media

Published: Mar 17, 2026, 5:19 AM EDT

Source: Information for this report was sourced from Boston.com

The Discovery of a Hidden Grave in Tyngsborough

A year long investigation into a missing person case reached a grim conclusion on March 16, 2026, when investigators discovered human remains buried in a residential garage. Shawn Sullivan, a resident of Audrey Avenue in Tyngsborough, was taken into custody following the search of his property. Middlesex County District Attorney Marian Ryan announced that the remains are strongly suspected to belong to Jill Kloppenburg, who disappeared in early 2025. Sullivan is scheduled for arraignment in Lowell District Court on charges that include murder and assault and battery with a dangerous weapon.

A Crucial Tip Leads to a Break in the Case

The breakthrough in the investigation originated in Nashua, New Hampshire, where a friend of the suspect approached local law enforcement. According to the District Attorney, this witness claimed that Sullivan confessed to shooting a woman named Jill at his residence approximately fourteen months ago. The informant further alleged that the suspect had buried the victim beneath the floor of his own garage. This report allowed Nashua police to connect the confession to the cold case of Jill Kloppenburg, who was last seen leaving her home on January 2, 2025, and was officially reported missing shortly thereafter.

Forensic Investigation of the Audrey Avenue Property

Executing a search warrant at the suspect's home, detectives utilized ground penetrating radar technology to inspect the garage area. The scan identified a suspicious five by three foot section of the floor that appeared to have been recently modified. Investigators noted that the surface consisted of an epoxy coating layered over cement, which showed clear signs of being cut and patched. The forensic process to penetrate these layers was described as extensive and delicate, as teams sought to reach the subfloor without compromising potential evidence hidden below the industrial materials.