A Michigan man, aged 59, is facing a life sentence after being convicted of murdering his girlfriend of two decades. The man reportedly strangled her using his forearm during a heated dispute over their living arrangements, later admitting to authorities that he had “snapped.”

In a ruling on Monday, Ottawa County Circuit Judge Karen Miedema sentenced Randall Alan Grinwis to a term ranging from 32 and a half to 90 years in a state prison for the 2024 killing of 63-year-old Donna Hyma, according to court documents.

The sentence followed a jury’s decision earlier in the month, which found Grinwis guilty of second-degree murder. Additionally, he was convicted of felony larceny for taking $1,800 from Hyma’s brother shortly after committing the murder.

During the sentencing, Hyma’s family expressed their deep sense of betrayal, highlighting that Grinwis was someone they had trusted for many years.

“I trusted him with her life, and now I have to live with that for the rest of mine,” Lisa Vanderyacht, Hyma’s daughter, emotionally stated in court.

Vanderyacht shared that her loss was twofold: not only had she lost her mother, but she also lost the image of the man she once thought Grinwis was.

“I lost two people that day — my mother and the man I thought I knew for 20 years,” she said, adding, “We trusted him.”

She also rejected any suggestion that the killing was a momentary lapse, borrowing the defendant’s own words to make her point.

“Nothing about that day was different,” she said. “He just snapped.”

But according to prosecutors, saying Grinwis “snapped” actually underplayed his level of culpability in Hyma’s death. The state continued to assert that the violence he inflicted on his girlfriend was far from instantaneous, emphasizing the sustained nature of the attack.

“This was not a snap,” a prosecutor said. “He had 40 seconds to change his mind, but he continued pressing down on her, and that cannot be overlooked.”

Miedema, in imposing the lengthy sentence, called the case “a very sad situation,” stressing that the killing was preventable.

“This was an incident that could have been totally avoidable,” the judge said. “You had options … but you chose a very drastic and very evil option.”

Grinwis declined to make a statement before sentencing.

As Law&Crime previously reported, the killing happened on New Year’s Day 2024 inside the couple’s Zeeland Township home following an argument over living arrangements.

Hyma was found unresponsive on a couch after deputies conducted a wellness check. An autopsy later determined she died from asphyxiation, and her death was ruled a homicide.

Prosecutors said Grinwis used his forearm to press against Hyma’s throat, suffocating her. He later checked for a pulse and breathing to confirm she was dead, according to court documents.

After the killing, Grinwis stole money from the victim’s brother and fled the state. He traveled through the Midwest before flying to Las Vegas, where he stayed in a hotel and gambled until he ran out of money.

Investigators said Grinwis eventually turned himself in to police, though prosecutors alleged he did so only after exhausting his funds and told authorities he would have “kept running” if he had the means.

A recording of the confession was played during trial, with jurors hearing Grinwis telling detectives how he just “snapped,” according to a report from The Sentinel.

“She was saying some really crazy s— and I’m telling on myself right now and I snapped,” he said on the tape. “I don’t know how else to say it.”

He went on to say that he could not remember exactly what made him lose his temper.

“I don’t know what made me snap,” Grinwis reportedly said. “I honestly don’t. That’s what hurts the most for me.”