ALFRED — Derek Poulin showed virtually no emotion Friday afternoon as jurors returned a guilty verdict in his trial for the 2012 murder of his grandmother in Old Orchard Beach, a crime the state’s prosecutor said was carried out with “extreme cruelty.”

After less than three hours of deliberation, the jury found Poulin guilty of both murder and arson for beating and stabbing Patricia Noel, and then setting her body and her home on fire.

Poulin, 26, faces sentencing in a month to six weeks, and Assistant Attorney General Donald Macomber said he expects the state to recommend a life sentence because of the brutal nature of his crimes.

Poulin faces 25 years to life in prison for murder and up to 40 years in prison for arson.

Poulin’s attorney, Amy Fairfield, said she was not surprised by the verdict, but believes the case was improperly investigated. She has not decided whether to file an appeal.

“I think he’s overwhelmed and shocked,” she said of her client. “I don’t think it has sunk in.”

Poulin was suspected early on in the brutal slaying of his grandmother on Oct. 23, 2012. Noel’s body was found inside her Old Orchard Beach home after a neighbor called 911 to report that the house was on fire.

An autopsy revealed that Noel was beaten with a wrench and a golf club, stabbed 72 times with a paring knife, and then her body was set on fire. She was 61.

Because the fire destroyed the physical evidence of Noel’s murder – including any fingerprints or DNA on the three murder weapons – the state’s case hinged almost entirely on circumstantial evidence.

However, Macomber said in his closing argument Friday morning that it all pointed to Poulin.

He described Poulin as an “unemployed, unmotivated pot smoker” who became angry and decided to kill Noel because she wanted him to move out of her home.

The state said Poulin’s statements about his whereabouts the day of the murder did not match the timeline investigators put together with witness statements and other evidence.

For instance, Poulin said he went to Portland about noon to run errands, including a visit to the Bureau of Motor Vehicles. But video showed that he was there about 4 p.m., well after Noel was murdered.

Macomber also said when Poulin turned over the clothes he was wearing that day to investigators, they did not match what he was wearing in the video.

Finally, even after learning that his grandmother had been killed, Poulin stopped at a store to buy a pair of pants before returning to Old Orchard Beach.

Fairfield built her defense on the possibility that someone else could have committed the crime, specifically Reginald Poulin, the victim’s son and Derek Poulin’s father.

Fairfield said Reginald Poulin was working that day for a lawn care company, but he was alone and his whereabouts were unaccounted for during the late morning and early afternoon hours. And his vehicle’s GPS device was turned off.

“It’s a horrific crime. Unforgivable,” she told the jurors. “Somebody needs to be held accountable, but that person is not Derek.”

Before the trial, Fairfield also argued that Poulin was not competent, but Justice John O’Neil ruled otherwise.

Poulin did not testify in his own defense, but O’Neil instructed the jury not to assign any weight to that fact in its deliberations.

During closing arguments, Poulin sat stoically with his hands folded in his lap and didn’t look at the jurors or the audience, which included his aunt, Darcy Daniels, sitting in the front row.

Daniels wept as the jury read the verdict and hugged the state’s victim witness advocate. She declined to speak with reporters outside the courthouse.

Assistant Attorney General Leane Zainea, the state’s lead prosecutor, said she was pleased with the verdict.

“This was a very difficult period for the victim’s daughter,” she said. “She’s been waiting a very long time for justice.”

Although Fairfield was noncommittal on an appeal, she said she thought the case was “fraught with evidentiary issues.”

“I think there were some missteps along the way through the investigation,” she said.