OLD ORCHARD BEACH – The grandson of a woman who died in a fire at her home last Tuesday has been arrested and charged with murder and arson.

State police said they arrested Derek Poulin, 23, at his mother’s home on Brighton Avenue in Portland Saturday afternoon.

Poulin is charged with killing his grandmother, Patricia Noel, 62, and with arson.

Steve McCausland, spokesman for the Maine Department of Public Safety, said the arrest came after police got lab results on evidence that had been taken from the scene, but he did not immediately say what that evidence was or what information was obtained from the lab results.

Police had earlier said that Poulin and his father, Reggie Poulin, had lived in Noel’s house on Wesley Avenue. The fire was reported Tuesday afternoon and officials said it started in the first-floor room where Noel slept.

Firefighters discovered Noel’s body after putting out the fire. A cause of death has not been released, but McCausland said that information will probably be provided when Poulin makes his first appearance in court, which is expected to be Monday or Tuesday.

Poulin is currently being held at York County Jail.

The day after the fire, Poulin said that police had taken his cellphone, but would not tell him why. He also said that he had been barred from returning to the Old Orchard Beach home to collect his belongings.