AUBURN — The adoptive mother of a Massachusetts man murdered last year by a Lewiston man said Wednesday she hoped his killer “serves every single second” of his 33-year sentence behind bars.

Mark J. Sinclair Androscoggin County Jail

Mark J. Sinclair, 30, pleaded guilty in Androscoggin County Superior Court last week to intentional or knowing murder, a crime punishable by 25 years to life in prison.

On Wednesday, Justice Jennifer Archer imposed the negotiated sentence after hearing from the family members of John Paquin, 20, of Worcester, Massachusetts.

Shirley Paquin said her adopted son was still figuring out who he was when his life was cut short by the July 17, 2022, shooting in Lewiston, which she called a “reckless and senseless act.”

She said she wanted Sinclair to know “how deeply his actions have affected so many people.”

Paquin said her initial hate for Sinclair had gradually evolved into sorrow for him.

“One day, he will feel remorse,” she said. “I know he will.”

And when Sinclair does come to terms with what he’s done, she said, “it will eat away at him like a cancer, the taking of the life of somebody else.”

Paquqin said: “I understand that the defendant has children of his own and I will never ever wish this kind of heartache and pain on him.”

John Paquin’s aunt, Delores Saka, told the judge, “I hope this monster suffers daily with the memory of what he has done. May God have mercy on his soul because I will definitely not forgive him for the horrible act.”

Assistant Attorney General Leanne Robbin said Sinclair had gunned down Paquin with premeditation, calling his killing “more like an execution.”

Video footage captured by city surveillance cameras showed two people matching the descriptions of Sinclair and another man standing close to each other while talking to Paquin in the area of 32 Howe St. in Lewiston.

Paquin held his hands behind his back, apparently holding a knife, while looking at the two men.

Sinclair can be seen in the video shooting John Paquin with a handgun multiple times, police said.

After Paquin fell to the ground, face down, Sinclair was seen approaching him and shooting him again in the back of the head.

Sinclair and the other man then fled the scene toward 12 Howe St., where Sinclair had been staying.

At Sinclair’s apartment, police executed a search warrant and found a 9 mm Taurus handgun on the kitchen counter. Evidence technicians had recovered six 9 mm shell casings at the scene of the shooting.

In the apartment, police also found a pair of black jeans, a belt and a black sweatshirt in a bedroom. A bank card belonging to Sinclair was found in a pocket of the jeans.

A state firearms examiner concluded that the casings and bullets from the crime scene and Paquin’s autopsy had been fired from the firearm recovered from 12 Howe Street.