Gregory Groom, of Rehoboth, confessed to police that he stabbed Kylee Monteiro multiple times with a kitchen knife, according to prosecutors.

The day before prosecutors say her boyfriend stabbed her three times, 18-year-old Kylee Monteiro sent an ominous warning to her sister: "If I die it was Greg."

Kylee Monteiro was last seen on Aug. 7 in the area of County Street. Police charge her boyfriend with murder after finding human remains at his home.

Monteiro was nearly three months pregnant at the time, her family said, as previously reported by WCVB and WBZ. She had told a friend — one of the last ones to see Monteiro alive — that she was not feeling safe. "She was like 'I don't feel safe right now something's not right,'" the friend reportedly said, per WCVB.

A Rehoboth man charged with murder reportedly drew a map pointing to a five-foot hole that he dug to bury his pregnant 18-year-old ex-girlfriend in after he stabbed her to death with a kitchen

The boyfriend of a missing 18-year-old pregnant woman is now facing assault and witness intimidation charges while police continue to search for Kylee Monteiro in Rehoboth.