HUDSONVILLE, Mich. (WOOD) — A Grand Rapids Community College instructor is headed to trial, facing a maximum of 15 years in prison after his son with autism drowned in the family’s backyard pool.

Timothy Koets appeared at an Ottawa County court Thursday where the case was laid out in an all-day hearing.

He was charged in October with manslaughter and child abuse in the drowning death of his 16-year-old son who died in the icy outdoor pol.

Today’s hearing centered on whether Koets made sure that his wife was watching out for the boy when he left his home near Hudsonville to go to work in downtown Grand Rapids March 28.

In the Hudsonville courtroom, a judge said she had no doubt that Koets acted with negligence, knowing that his son was in potential danger when unsupervised.

Forensic pathologist David Start said the victim, Sam Koets, died from cold water drowning.

Assistant Prosecutor Paul Kraus presented the case and showed photos of the teen and backyard pool with ice floating in it where he drowned.

The teen’s pediatrician said Sam Koets had the cognitive development of a child younger than 2-years-old.

“I found mother holding a child still within the swimming pool,” Ottawa County Sheriff’s deputy Eric Smith said.

When Smith was asked if the teen’s arms were bound in any way, he said they were.

The judge heard the detective’s recording of an interview with the defendant explaining that his son’s arms were restrained in order to keep him from harming himself and others.

In the recording, Timothy Koets said he woke up his wife when he left for work and assumed she was taking care of the teen. He allegedly told detectives he wished he had made sure she was really awake and aware, but he was running late for work.

Prosecutors showed dozens of text messages that went between Timothy Koets and his daughter after she came home to find her brother in the pool. She said she tried to get him to come out of the pool, but says he wouldn’t.

A photo shown in court of Sam Koets in the pool on the day of his death.

The series of text messages went on for more than 30 minutes. She texted her dad a photo of Sam in the pool. Her father allegedly replied saying, “make sure the freak is OK.”

Timothy Koets told his daughter that he would be home in a while, she says.

She then went to wake up her sleeping mother.

“When I told her that Sam was in the pool, she woke right up and ran outside,” the victim’s sister said. “I knew that she was sleeping because my dad told me that she was sleeping.”

Police, paramedics and Child Protective Services workers took to the stand to say they visited the Koets’ home many times over the years after the boy had escaped his yard and was found wandering.

Each time, the workers say they reminded Timothy Koets that his son could never be left unattended. Despite the visits, formal action was never taken against him.

The judge did send the most serious charge of manslaughter to felony court, but she is withholding judgement on the additional charges of child abuse for at least two weeks.