BANGOR, Maine — The man Nathaneal Nightingale’s attorney has named as an alternative suspect in the slayings of a Webster Plantation couple in 2009 did not take the stand Friday morning as planned.

Matthew Miller, 26, of Webster Plantation instead invoked his Fifth Amendment right against self-incrimination while jurors were out of the courtroom on the fifth day of Nightingale’s trial at the Penobscot Judicial Center on two counts of intentional or knowing murder.

Instead, defense attorney Jeffrey Silverstein called two Maine State Police detectives who testified that they had interviewed Matthew Miller at least twice in the three weeks after his parents were found shot to death in the kitchen of their Tucker Ridge Road home on Nov. 28, 2009.

Detective Carleton Small told the jury that Matthew Miller had admitted in an interview on Dec. 2, 2009, to trying to sell a combination VCR-DVD player to his father the night before his death so he could obtain money to buy drugs. Small said Miller Sr. had refused to give his son money but kept the player to put toward his son’s $1,500 debt he owed his father.

The detective also testified that the next morning Miller obtained drugs from an elderly couple who lived in Lee, then drove a short distance away, pulled into a camp road and injected the narcotics. Small said Matthew Miller told him that he heard sirens pass by while he was on the camp road.

Nightingale, 32, of Burlington was arrested on Dec. 12, 2009, after he confessed to investigators. He was indicted by the Penobscot County grand jury later that month and pleaded not guilty to the charges in March 2010.

Assistant Attorney General Andrew Benson, who has argued that the motive for the killings was money, rested the state’s case Thursday afternoon after playing for jurors a recorded interview in which Nightingale confessed to an investigator.

Nightingale told Maine State Police Detective Dale Keegan in the interview played for the jury that he took his stepfather’s .22-caliber revolver to the Millers’ home the morning of Nov. 28, 2009, to pawn it for money to buy illegal painkillers because he was out of a job and broke. The defendant said he was showing Miller Sr. that the gun worked when it went off and hit Miller Sr. in the back of the head.

“I was showing them the gun, holding it,” he said in the recording. “I had it cocked and I pulled the trigger. A shot went off and he fell. She turned and looked at him and I shot her. I don’t know where I shot her. I know it wasn’t me. It was desperation.”

Dr. Margaret Greenwald, the state’s chief medical examiner, testified Monday that both Millers died of small-caliber gunshot wounds to their heads.

In his initial interview with police, played for jurors Tuesday, Nightingale denied shooting the Millers.

“I would never do that,” Nightingale said in that interview, recorded on Nov. 29, 2009. “I respected them. There would be no reason to kill them. They’ve been very good to me.”

Nightingale has been held without bail at the Penobscot County Jail.

Testimony for the defense is expected to conclude Friday afternoon, but the jury will not begin deliberating the case until Tuesday, Superior Court Justice William Anderson, who is presiding over the trial, said Thursday.

If convicted, Nightingale would face a minimum sentence of 25 years and a maximum sentence of life in prison on each count.