HOULTON — A man charged with stabbing a 10-year-old boy, the boy’s father and a family friend at a home in northern Maine was convicted today of three counts of murder, as well as one count of arson stemming from an attempt to destroy evidence.

The jury returned its guilty verdicts on all counts after deliberating for three hours in the trial of Thayne Ormsby in Superior Court in Houlton.

Testimony resumes Tuesday in the trial’s second phase, which involves testimony about the mental state of Ormsby, who’s using an insanity defense.

Ormsby, 23, confessed in a videotaped interview shown to jurors that he killed 55-year-old Jeffrey Ryan, Ryan’s 10-year-old son, Jesse, and a family friend, 30-year-old Jason Dehahn, on June 22, 2010.

“What he told the detectives and what you heard him say is totally consistent with the evidence,” said Deputy Attorney General William Stokes. “The defendant thought he had silenced all the victims. But now, almost two years later, the evidence speaks for Jeffrey Ryan, Jesse Ryan and Jason Dehahn.”

Defense attorney Sarah LeClaire suggested that Robert Strout, with whom Ormsby was living at the time, might have been responsible for the crime.

Strout, who pleaded guilty to hindering apprehension and arson, admitted helping Ormsby set fire to Jeffrey Ryan’s pickup truck and to taking Ormsby to New Hampshire. Strout is expected to be sentenced sometime after Orsmby’s trial concludes.

In Maine, murder carries a maximum sentence of life in prison. Those who’re deemed not criminally responsible for their actions are sent to a psychiatric hospital.

Before returning their verdicts, jurors asked for clarification on the charges against Ormsby and to have testimony from the state’s former chief medical examiner, Dr. Marguerite DeWitt, read back to them. The judge also repeated the elements of proof required for the jurors to find Ormsby guilty.