US man kills wife & 6 children, sets house on fire, turns gun on himself after wife accused him of affair with intern

A Michigan man shot and killed his wife and six children before setting their home on fire and turning the gun on himself, in what police have ruled a murder-suicide.

His wife had supposedly written online about her husband's alleged affair with a younger intern.

According to New York Post, Kristopher Karolkiewicz, 47, allegedly shot his wife Amanda "Mandy" Karolkiewicz, 39, and their six children, aged 5 to 15, at their Grand Haven Township home before setting it on fire.

The bodies were discovered at around noon on Friday when the home was found on fire.

The Ottawa County Sheriff's Office confirmed that autopsies determined all family members died of gunshot wounds, and that the husband took his own life.

Authorities also said multiple fires appeared to have been intentionally set throughout the house after the killings.

The family's pets also died.

Wife's alleged Reddit posts

Two years before her death, Mandy had allegedly written about her husband's infidelity in posts on Reddit under the username MandyK1179, according to local media Holland Sentinel, which independently confirmed the authenticity of the account.

In one 2024 post, she explained how she had originally met her husband while working as an intern, and alleged that history had since repeated itself.

She supposedly wrote: "He was divorced and older than me… fast forward ten years and five kids, he was cheating with the intern again — the same age I was when I was the intern."

She wrote about the emotional toll the alleged affair took on her, describing a year of self-loathing before she realised she had been the one suffering for what he had done.

She reportedly wrote that she only worked to repair the marriage because of the children they shared.

She allegedly wrote: "I kept telling myself, 'I love my kids more than I hate my husband right now.' They have no idea — I faked it 'till we made it. We're in a much better place 4.5 years out, but it's still a fight to stay in a healthy place."

In another post, she also wrote that the idea of leaving her husband was “insanely terrifying," according to the Holland Sentinel.

Family can't confirm authenticity of Reddit posts

The family's spokesperson, Emily Jones, told News8 that the family could not confirm the posts were written by Mandy.

She added:

"It's very clear that whoever wrote that, they were using Reddit as an outlet to seek support in a bit of anonymity, because for whatever reason, they felt they couldn't seek it in their real lives. I think that that's sad in and of itself, whether it was Mandy or somebody else."

Background

According to New York Post, the couple met at a beverage company in 2008 and married in August 2009, according to a parenting-focused blog Mandy had.

They had been together for nearly 17 years at the time of their deaths, and had six children together: three biological sons, two adopted daughters and another biological son.