GRAND RAPIDS, Mich. (WOOD) — A defendant convicted of a brutal triple murder as a teen will be back in court this week for a sentencing hearing for a third time.

Jon Siesling, now 37, was convicted of murder in 2003. The trial revealed Siesling, 17 at the time, used a baseball bat to beat his mother and 15-year-old sister Katelin before stabbing them with a kitchen knife, then slit the throat of his 6-year-old sister Leah in their Walker home in January of that year. Siesling received a mandatory sentence of life in prison without parole.

In 2012, the U.S. Supreme Court decided mandatory life sentences were unconstitutional for anyone 17 and younger. The argument behind the decision was expert opinion that the human brain isn’t fully developed until the age of 25. In 2016, juvenile lifers, including Siesling, were ordered to be sentenced again.

“We now have the burden of showing we need to impose a larger sentence, life without parole,” Kent County Prosecutor Chris Becker, whose office argues for the people at the resentencing hearings, said.

In 2021, a judge ruled Siesling should stay in prison for life.

Then, in July 2022, the Michigan Supreme Court ruled mandatory life was unconstitutional for anyone convicted at age 18 or younger. That meant some people would go through resentencing for a third time.

Along with concerns a killer’s sentence could be reduced, the resentencings are a burden on prosecutors, with staff having to dig up long-stored files and track down witnesses.

That’s nothing compared to the emotional toll it takes on families.

“Years ago, they had to go through the trial and thought it was over. But now here, some of these families are going through their second and maybe looking at their third resentencing because things keep changing and they think it’s over,” Becker said. “There’s no finality. It’s just picking at an open wound.”

There’s talk in the Michigan Legislature of increasing the age to 21.

“The whole premise of the changing of the law is that the juvenile brain doesn’t form until your 25. So there’s argument in the appellate defender’s office that pretty much said, ‘Yeah, we think this ought go up to maybe 25.’ So we could see up into the 20s now,” Becker said. “The Prosecuting Attorneys Association of Michigan is meeting with the legislators and we’re trying to educate the legislators in Lansing that hey, there are consequences to these changes.”

Becker’s office is already dealing with dozens of resentencings for 18-year-olds.

“Probably 20, 30, at least just right now in terms of 18-year-olds that we started to take a look at,” Becker said. “We start talking open up to 21 years old, I shudder to think.”

He’s not convinced by the experts’ arguments.

“I’m not going to sit here and argue with science. But still, a lot of these cases come down to you know fairly young in terms of harm you’re inflicting on another person and how to kill or not to kill,” Becker said. “Those are not that complex an issue, of knowing right from wrong.”

Sielsing’s hearing is set to begin Thursday and continue through Friday at the Kent County Courthouse.