Left: Gregory Groom (WBZ). Right: Kylee Monteiro (GoFundMe).
A Massachusetts man who stabbed his girlfriend to death at his home before burying her in a 5-foot grave and calling cops to report her missing, claiming she stormed off following an argument, is headed to prison.
Gregory Groom, 23, pleaded guilty to second-degree murder and witness intimidation in the death of 18-year-old Kylee Monteiro in Rehoboth, which is some 50 miles southwest of Boston. A judge sentenced him to life in prison with the possibility of parole for the murder and three to five years for witness intimidation. The sentences will be served consecutively.
Faith Monteiro, the victim's sister, in recent weeks has asked supporters on Facebook to email the Bristol County District Attorney's Office to reject the plea deal that would allow Groom to be released from prison. He was originally facing a first-degree murder charge, which would put him in prison for life.
The family feared Groom could serve less than 20 years.
"How can you call that justice?" she said in a September interview with local Fox affiliate WFXT. "Two lives were lost, and he's not even going to serve the lifetime of the kid he should be raising."
According to prosecutors, Groom called Rehoboth cops on Aug. 8, 2025, and told them Kylee Monteiro had been at his home two days prior, looking for a place to stay. He claimed they got into a verbal spat and she left his home, and she hadn't been heard from since, District Attorney Jason Mohan told the judge at a previous court hearing. Groom told investigators that his girlfriend was typically active on social media but had not posted since he last saw her.
Detectives then spoke to Monteiro's sister, who received a text message from Monteiro on Aug. 6, 2025, that allegedly read "he threw me on the ground and pulled my hair and strangled me. My phone is at 4% and if I die it was Greg." Family members said they contacted her but could not reach her.
Prosecutors noted at the hearing that Monteiro was 11 weeks pregnant at the time of her death.
Cops went out to Groom's home on Aug. 14, 2025, to search the 25-acre property with cadaver dogs and an emergency response team but found nothing.
Groom spoke with investigators a second time. During that interview, he allegedly admitted to having an altercation with his girlfriend. During the argument, he said he knocked her cellphone out of her hand. Detectives told Groom that they were again going to search his property and "dig if necessary."
"Mr. Groom then paused," Mohan said. "He was given an opportunity to tell the police where Ms. Monteiro's body was located either by being taken to his property and pointing it out or drawing a map or telling officers where her body was located, as they believed Ms. Monteiro was dead."
The defendant then drew a "rudimentary" map that showed a shed on the property. He allegedly told cops that he stabbed Monteiro twice in the neck and once in the chest on Aug. 6, 2025. The kitchen knife broke off when he stabbed her in the chest, he said. She died, and Groom spent that night and early morning hours the next day digging a grave. Once the hole was five feet deep, he pushed her body in and buried her.
Crime scene investigators went to the shed where they saw a large pile of brush. Under the brush, they found a pool of blood where Groom is believed to have killed his girlfriend. About 20 yards away, cops found "feet upon feet" of cut-down trees. They pushed the trees to the side where they found freshly moved dirt.
Monteiro's body was in the hole.
She was pursuing a welding career and had graduated from high school just months before her death.
"Kylee was a bright and spirited young woman who graduated from Attleboro High School in 2025," her obituary said. "With a passion for welding, she proudly earned her welding certificate and was eagerly looking forward to a promising career in the field. Her vibrant personality shone through her love for posting on the internet and interacting with her friends."