Dustin Bentley, 30, has been charged with murder in the alleged beating and stabbing death of his roommate, 65-year-old William Popplewell.
Bentley said nothing during a court appearance Wednesday, mostly keeping his head down and away from the cameras.
Investigators said the first call to them came from Bentley's mother Monday night. She lives in North Carolina.
When police arrived, they found Popplewell's body inside their apartment on Boisvert Street near the beach.
Bentley's stepfather spoke to WGME on Wednesday.
"Dustin, he's a good kid. He grew up with a heart of gold. It's just so unlike him to do anything like this. That's all I got to say. I love the kid. He'll always be in my heart," he said.
But neighbors at the apartment complex paint a very different picture of Bentley.
Two neighbors, who did not want to be interviewed on camera, told WGME Bentley had been nothing but trouble since he moved to Old Orchard Beach in mid-December, describing him as volatile, loud and confrontational.
One of the neighbors said Monday night that he heard Bentley screaming in the apartment for about an hour and a half, saying things like, "What did I do? What did I do?" Later that night, when police arrested Bentely, that neighbor said Bentley had a pair of box cutters in his hands and that officers had to tackle Bentley and put him on the ground in the parking lot.
That same neighbor said he overheard Bentley telling police he was defending himself.
Bentley's stepfather also said he believes Bentley acted in self-defense.
Right now, court paperwork in the case hasn't been released, and prosecutors aren't saying yet what the motive is.
Police said that before they moved to Old Orchard Beach, the two men stayed at the Oxford Street Shelter in Portland.
Bentley is being held without bail. His next court appearance is scheduled for May.