Woman Charged in Fiance's Stabbing Death

Tonia Piontek claims self-defense after fatal altercation in their Green Bay home.

Apr. 10, 2026 at 3:23pm

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An extreme close-up of a kitchen knife, its blade stained with a dark liquid, against a pitch-black background, conveying the gritty, investigative nature of this crime scene.A brutal stabbing exposes the tragic consequences of domestic violence and the complex legal questions surrounding self-defense claims.Green Bay Today

Tonia Piontek, 46, has been charged with first-degree intentional homicide with modifiers for domestic violence and use of a deadly weapon after allegedly stabbing her 41-year-old fiance to death during an argument at their Green Bay, Wisconsin home in April 2025. Piontek called 911 that night, telling dispatchers she had just stabbed her boyfriend and didn't think he was okay, claiming she used a knife to defend herself as he 'came at' her during their fight.

Why it matters

This case highlights the complex dynamics of domestic violence, with Piontek's defense arguing she was a victim, while prosecutors allege premeditated murder. It raises questions about how the legal system handles cases of intimate partner violence and the use of lethal force, especially when the parties have a history of conflict.

The details

According to the criminal complaint, Piontek and her fiance had been drinking and arguing when the fatal stabbing occurred. Piontek allegedly used a 'pastry chef knife' to stab her fiance in the chest, killing him. Police found the victim on the kitchen floor in a pool of blood. Piontek showed officers bruising on her arms, which she described as 'normal' for her. She invoked her right to an attorney and did not make any other statements to police.

  • On April 13, 2025, Piontek called 911 at 10 p.m. to report the stabbing.
  • Piontek's next court appearance is scheduled for August 17.

The players

Tonia Piontek

A 46-year-old Wisconsin woman charged with first-degree intentional homicide for the stabbing death of her 41-year-old fiance.

Piontek's Fiance

The 41-year-old victim who was fatally stabbed by Piontek during an argument in their Green Bay home.

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What they’re saying

“I just stabbed my boyfriend, I don't think he's okay. Someone needs to get here now!”

— Tonia Piontek

“He came at me. I often keep a knife nearby to protect myself and he's just got ya know (inaudible), I didn't know what else to do, he's a lot bigger than me.”

— Tonia Piontek

What’s next

Piontek's defense attorney is working on a plea deal and waiting for a report from a domestic violence expert before her next court appearance on August 17.

The takeaway

This tragic case underscores the complexities of domestic violence situations, where victims may feel compelled to use lethal force, even as prosecutors allege premeditated murder. Piontek's defense is arguing she was a victim, raising questions about how the legal system handles such cases and the use of deadly force in intimate partner conflicts.