A Tyngsborough man has been arrested on murder and related charges after investigators found human remains buried beneath the floor of his garage, though authorities say the victim has not yet been formally identified.
Middlesex District Attorney Marian Ryan said 40-year-old Shawn Sullivan of Tyngsborough was taken into custody Sunday after detectives executing a search warrant at his Audrey Avenue home uncovered a bag containing human remains under a patched section of the garage floor.
Sullivan is expected to be arraigned in Lowell District Court on charges including murder, assault and battery with a dangerous weapon causing bodily injury, and improper disposal of human remains. It was not immediately clear if he had retained an attorney, according to NBC Boston.
The Office of the Chief Medical Examiner confirmed that the material recovered under the garage is human remains, but has not completed a formal identification or determination of cause of death.
Investigators have said the remains are believed to be those of 47-year-old Lowell woman Jill Kloppenburg, who was reported missing in early 2025, but stressed that identification is still pending.
According to Ryan, the investigation began on March 10 when Nashua, New Hampshire, police received a tip from a friend of Sullivan who reported that Sullivan had claimed he shot a woman named Jill at his Tyngsborough home in January 2025 and buried her under his garage floor.
Nashua officers linked that report to an existing missing person case for Kloppenburg, who had been last seen leaving her Lowell residence on Jan. 2, 2025, and later reported missing to Tewksbury police, the Boston Globe reported.
On Sunday, Tyngsborough police and Massachusetts State Police used ground-penetrating radar to examine a large, visibly patched area of the garage floor, roughly three feet by five feet, and detected an anomaly beneath the surface.
Working with the medical examiner, investigators cut through layers of epoxy and concrete over several hours before locating a plastic bag that was removed and later confirmed to contain human remains.
Tyngsborough Police Chief Shaun Woods said the case represents a tragic loss of life but emphasized that investigators believe the killing was not a random act and that there is no broader threat to the public. The district attorney's office said the investigation remains active and urged anyone with information to contact the Massachusetts State Police, as per Yahoo News.
