MADISON, Wis. (AP) — A jury on Thursday found a former Wisconsin sheriff’s deputy with Lou Gehrig’s disease not legally responsible in the killing of his wife and sister-in-law.

Andrew Steele, 40, will be committed for life to the Wisconsin Department of Health Services, which will conduct a predisposition investigation. The presiding judge, Nicholas McNamara, will then decide whether Steele, a native of Saginaw Township, Michigan, should be sent to an institution or released.

Steele showed little emotion as a judge in Dane County read the verdict early Thursday after a jury deliberated for about 10 hours through the night.

Defense attorney Jessa Nicholson was one of the lawyers who convinced jurors that Steele suffered from a neurocognitive disorder as a result of the disease.

“I’m proud that the science triumphed over the emotion, I’m proud that the jury was conscientious, that they listened to all of the evidence and they reached the right result,” Nicholson said.

Steele, a former Dane County deputy, pleaded not guilty by reason of mental disease to two counts of first-degree intentional homicide in the Aug. 22 deaths of his 39-year-old wife, Ashlee Steele, and her sister, 38-year-old Kacee Tollefsbol of Lake Elmo, Minnesota.

Ashlee Steele was strangled with a plastic zip tie and shot in the head at the couple’s home near Madison. Tollefsbol was beaten and shot in the lower abdomen, but managed to call 911. Steele tried to kill himself with carbon monoxide by lighting charcoal in the laundry room of the home, investigators said.

Prosecutors said Steele suffered from a depression disorder but was not insane, and that he planned the murders.

“Obviously we’re very disappointed in the jury’s verdict,” said Assistant District Attorney Paul Barnett, “but we do respect the process and we do respect the verdict. We do disagree with it.”

Lou Gehrig’s disease, also called amyotrophic lateral sclerosis, or ALS, attacks motor neurons, cells that control muscles.

Assistant District Attorney Andrea Raymond said that the defense’s case “vilifies people with ALS,” and implied that the 10 to 20 percent of people with ALS who also have frontotemporal dementia could commit violent acts like Steele, the State Journal reported.

“Reality and common sense tells you this is nonsense,” she said.

Nicholson said she hoped that the verdict would lead to further study of the relationship between criminality and brain damage.

“Brain disorders should be looked at in the context of the legal system,” Nicholson said. “I think today does start to establish precedent that we need to take brain damage seriously and we need to look at the way that people’s functioning is affected by neurological issues rather than just traditionally psychological issues.”

The jury’s verdict was not unanimous, with two of the 12 jurors dissenting.

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