CARROLL, Iowa — A Minnesota man accused of killing clerks at two Iowa convenience stores in one day last fall was convicted Thursday of first degree-murder in one of the shooting deaths.

A Carroll County jury deliberated less than an hour before finding Michael Swanson, 18, of St. Louis Park, guilty in the Nov. 15 slaying of 61-year-old Shelia Myers at a Kum & Go store in Humboldt.

Swanson was 17 when he was charged in Myers’ death. He faces a July trial in the death of Vicky Bowman-Hall, 47, who was shot and killed at a store in Algona the same day.

The defense maintains Swanson was legally insane at the time of the shootings.

Michael Taylor, a psychiatrist who testified for the state as a rebuttal witness earlier in the day, said Swanson expressed no remorse for his crimes during an April interview, or in a letter and phone call from jail while awaiting trial. Taylor said Swanson did not have bipolar disorder, and understood his crimes, as well as right from wrong.

“Mr. Swanson is not suffering from any type of diagnosable psychiatric disorder,” Taylor said. “He was fully capable of understanding the nature of his acts and differentiating between right and wrong when he shot and killed Sheila Myers.”

Taylor said Swanson told him the slayings had been brewing inside his head since he was 13. Swanson said his original plan was to wait until he was 18 and kill his parents, because those were the first two people he wanted to kill, Taylor said.

“I have always been fascinated by death and violence, and it was something I wanted to do — murder, rape and cannibalism,” Taylor said Swanson told him.

Taylor testified that Swanson told the psychiatrist he had explained to his mother that killing someone was like tossing a bucket of water on someone just before they jump in a swimming pool because they were going to get wet anyway.

“From Mr. Swanson’s perspective, people are going to die anyway,” Taylor said. “What difference does it make whether they die when they’re 77, or if he shoots them.”

On Wednesday, Kathleen Swanson testified that in 2004 a psychiatrist told her that her son should be removed from society.

“Your son needs to be locked up, and there isn’t anything more I can help you with,” she said she was told. Her son was 11 at the time.

Kathleen Swanson told jurors her son was a problematic infant and adult, recounting how day care providers wouldn’t care for him because of behavioral problems, how he’d hardly sleep, and how she’d sought professional help for her son.

In a statement released after the jury’s verdict, Swanson’s parents expressed their “sympathies and condolences for the families, extended families, friends, and communities that were affected by this horrible tragedy.”

“What happened on November 15th was truly devastating to all of the families involved,” Bob and Kathleen Swanson said in the statement. “As parents, nothing has prepared us for this type of a tragedy. We had previously sought assistance and tried to get help for our son Michael, whom we love and we are heartbroken by these events. We hope the trial will present the desperate realities some families face whose children suffer from mental illness.”

Swanson, who also was found guilty of first-degree robbery, smiled as the verdict was read.

He will be sentenced to life in prison without parole at a later date.