Portland man agrees to plea deal in roommate’s stabbing death

A Portland man has pleaded guilty to manslaughter in connection with the stabbing death of his roommate late last year, avoiding a first-degree murder charge that could have carried a sentence of 25 years to life.

Domingus Nobrega entered the plea Monday in Cumberland County Superior Court as part of an agreement with the Maine Attorney General's Office. Under the deal, the 16-year state prison sentence he agreed to is expected to be imposed at a sentencing hearing later this year. Prosecutors asked that the hearing be delayed so the family of the victim, 43-year-old Matthew Merrick, can be present.

Merrick was found dead inside the apartment he shared with Nobrega on Nov. 30, 2024, after Nobrega called police late in the afternoon to report finding his roommate on the floor, according to Assistant Attorney General Kate Bozeman. A native of the Portland area, Merrick had worked for about a year as a cook at Andy's Old Port Pub on Commercial Street.

The state medical examiner's office later determined that Merrick died from stab wounds to the chest, Bozeman said in court.

According to Bozeman, a woman who had been staying in the apartment told police that she witnessed Nobrega stab Merrick. She said Nobrega then led her into another room and forced her to use ketamine with him before eventually releasing her and instructing her to call police and tell them a "Colonel drug dealer" had committed the murder. The woman, who did not know Nobrega by name, later identified him from a photo lineup. Prosecutors said Nobrega had written his phone number on her arm, which helped confirm his identity.

Investigators also recovered data from an Apple Watch they said belonged to Nobrega, which showed his heart rate spiked around the time they believe the killing occurred. Online search history from before his arrest showed that Nobrega had researched ways to leave the country and pursue Russian citizenship, Bozeman said.

In addition, police obtained Signal messages in which Nobrega allegedly admitted the stabbing to a friend and asked for help cleaning up. The friend refused. Prosecutors said that friend later died before the case could go to trial, contributing to the decision to negotiate a plea.

Nobrega was originally scheduled for a jury trial beginning Aug. 10 on a single count of murder. He had also filed more than a dozen motions ahead of Monday's hearing, including a request to replace his two court-appointed attorneys, William Maselli and Stuart Tisdale.

During the hearing, Nobrega told Superior Court Justice John O'Neil that he had agreed to the plea with the understanding that he could enter an Alford plea, which would have allowed him to acknowledge that the state had sufficient evidence to convict him while still maintaining his innocence. Bozeman said the state would not accept that arrangement. O'Neil noted at one point that he could tell from Nobrega's body language that he disagreed with the prosecutor as she laid out the evidence.

Maselli and Tisdale told the court that the defense had received all of the prosecution's evidence and that a jury could reasonably find Nobrega guilty of manslaughter based on what the state had gathered.

Manslaughter under Maine law carries a maximum sentence of 30 years in prison. A date for Nobrega's sentencing has not yet been set.