Authorities say a Michigan teen is behind bars after he allegedly fatally shot his mother last week while she slept
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Credit: Ingham County Sheriff

Authorities say a Michigan teen is behind bars after he allegedly fatally shot his mother last week while she slept, PEOPLE confirms.

Andrew David Willson, 19, was arraigned on Monday on murder and firearm charges in connection with the shooting of his 51-year-old mother, Lisa Marie, at their home in Wheatfield Township, Michigan.

“It is a tragedy all the way around,” Ingham County, Michigan, Sheriff Scott Wriggelsworth tells PEOPLE. “At his formal arraignment you had his father, his brother there and the parents of the victim. It was a brutally intense sad 10 minutes.”

Wriggelsworth says neither Willson nor the home he shared with his mom had a prior record of run-ins with the law.

Willson’s preliminary hearing is scheduled for Sept. 28. He is being held in county jail without no bail.

His defense attorney, Patrick O’Keefe, says they are still trying to gather information about the case. “I haven’t had a chance to look at all the facts and a chance to exam the government witnesses,” he tells PEOPLE. “It is really early in this process.”

However, O’Keefe claims that mother and son had a “good relationship” — in contrast to the allegations against Willson now.

“His mother was a very doting person and the two of them never had any problems,”O’Keefe says. “We haven’t seen any evidence thus far that there was any trouble between him and his mother.”

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Willson and his mother lived together, according to O’Keefe, and the teen had been taking college classes and working at a towing company.

Willson was diagnosed with Hodgkin’s lymphoma when he was 14, his attorney says.

“He had several rounds of chemotherapy and radiation,” O’Keefe explains. “According to his father he underwent some heavy dosage of chemotherapy when he was 14 and 15 — so much that the levels he was given [were] enough to kill an adult, but because he was a young person his body was able to tolerate it.”

“There is a phenomenon called ‘chemo brain.’ It can affect people who are going through chemotherapy and can cause an adverse effect on the brain,” O’Keefe continues. “I am not saying that happened to him, but that is something we would like to look into it.”

A Cover Story for a Cold-Blooded Killing?

Willson contacted police at 6:57 a.m. on Sept. 8 allegedly claiming he had returned home from a drive and found his mother dead, according to a felony warrant read at his arraignment by Ingham County detective Charles Buckland.

Police responded to the scene and found Lisa Marie’s body in her bedroom with a gunshot wound to the back of her head.

“Through the investigation, I interviewed Andrew Willson as being the only person in the house with Lisa Willson, who he identified as his mother,” Buckland said in court. “No one else lives in the house and no one else was in the house that day.”

Willson allegedly told police that he’d spoken with his mother around midnight, when he returned home from work, and “the conversation was about a puppy he had brought home a few weeks earlier that his mom wanted him to get rid of,” Buckland said. “And he was to take that puppy the next morning — which would have been the morning of the shooting — to his father’s home in Dansville.”

Willson then allegedly admitted that at some point during the night or early morning, when his mother was asleep, he grabbed a .22-caliber Magnum rifle from a locked cabinet, loaded the gun with ammunition and then went upstairs to her room — knowing she was asleep and vulnerable.

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In court at the arraignment, Buckland then described a chilling series of allegations:

“[Willson] walked in, stood at the side of her bed — [he] said that his mother was lying on her right side, so he was facing her back. He said he aimed his rifle at the back of her head; said he didn’t look down at the sight, he just moved the barrel so it was positioned at the back of her head, and he pulled the trigger.”

After Willson allegedly shot his mom, he said he left their house and drove around the back roads of Ingham County before he tossed the rifle, which police later found.

Sheriff Wrigglesworth declined to comment on Willson’s statements to law enforcement or his potential motive. Wrigglesworth says the killing, even with some possible answers, defies understanding.

“I couldn’t imagine going through this as a parent,” he says. “This is one that you can’t make rhyme [or] reason out of it.”