Prosecutors released additional details regarding the murder of an 18-year-old pregnant woman during the arraignment of her intermittent boyfriend, now facing charges related to her death.

Authorities report that Gregory Groom, 22, confessed to killing Kylee Monteiro and concealing her body on his property in Rehoboth, Massachusetts, as per ABC News.

Monteiro, who was twelve weeks pregnant and residing in a shelter for pregnant and homeless women, was last observed on August 6 when visiting Groom’s residence, as noted by CrimeOnline. Her family and friends mentioned she expressed feeling unsafe but subsequently ceased communications.

Groom reached out to law enforcement on August 8, stating Monteiro had been at his home seeking a place to stay, that they argued, after which she allegedly left, according to prosecutors in court on Wednesday. They further indicated that Groom claimed Monteiro “hadn’t been seen or heard from since,” in court.

Groom said the argument they had was over whether he would allow her to stay at his property.

Prosecutors stated that on the eve of her vanishing, she messaged her sister, Faith Monteiro, describing that Groom “threw me on the ground and pulled my hair and strangled me,” reported WJAR. At a certain point, Monteiro texted her sister that her “phone is at 4% and if I die, it was Greg.”

Despite her family’s attempts to relocate her to a secure environment, ABC News reported she was “attempting to continue to stay at Mr. Groom’s residence.”

Officials searched Groom’s 25-acre property on August 14 but found “nothing of significance.”

On Tuesday of this week, things changed dramatically when Groom reported to police for another interview. At that point, he told them that they’d argued and that he “pushed her, she fell backwards and she hit her head.”

Monteiro tried to contact someone, but Groom said he told her he would “knock her cellphone out of her hand,” prosecutors said.

Detectives further pressed Groom on Monteiro’s whereabouts, telling him the were “prepared to search the property and dig if necessary.”

At that point, prosecutors said, Groom drew a “rudimentary map” showing a shed on his property, telling them the argument took place behind that shed, WJAR reported. And he confessed that he had stabbed the teen “twice in the neck and once in the chest,” adding that the chest thrust broke the knife’s blade.

Then, he said, he spent “several hours” digging a hole in a woods about 20 yards from the shed, where he “pushed her body into a hole and covered it up,” ABC said.

Officers went to the property, where the found a “large pile of brush” and a “body consistent with Kylee Monteiro.”

The body is currently with the medical examiner for positive identification and an autopsy.

Groom has been charged with murder, assault and battery on a pregnant victim, assault and battery on a family or household member, and aggravated intimidation of a witness, juror, police, or court official.

Bristol Count District Attorney Thomas M. Quinn said after the hearing that it was “still too early” to determine a motive for the murder.

Groom is being held without bond and is due back in court next month for a probable cause hearing.