Woman Accused of Fatally Stabbing Fiancé With Pastry Chef Knife During Domestic Fight

A Wisconsin woman is facing a homicide charge after stabbing her fiancé to death during a fight at their home in Green Bay.

The 46-year-old woman, Tonia Piontek, is accused of using a pastry chef knife in the fatal stabbing. The victim was a 41-year-old man whom investigators believe was Piontek’s fiancé.

Authorities added domestic violence and weapons-use modifiers to the charge because the incident allegedly occurred during a domestic dispute.

According to Law & Crime, the incident took place on April 13, 2025, at the couple’s home on Smith Street. Authorities said Piontek called 911 around 10 p.m. that night.

During the call, she said the two had been drinking and arguing. “We’ve been fighting, he came at me,” Piontek reportedly told the dispatcher.

She also said, “I often keep a knife nearby to protect myself,” and, “I didn’t know what else to do, he’s a lot bigger than me,” Piontek said.

The dispatcher reported that Piontek sounded upset and repeatedly asked for help. Inside the home, officers found the victim lying on the kitchen floor with apparent injuries.

Police reported that a knife was recovered at the scene. An autopsy later determined the fatal injury was to the chest.

Investigators described the weapon as a pastry chef's knife measuring about 7.87 inches long.

According to police reports, Piontek admitted to using the knife.

When officers arrived, they found Piontek outside the home and observed bruising on her forearms.

She reportedly showed the bruises to officers and said they were “normal” for her. Authorities said it remains unclear whether the bruises were related to prior incidents or sustained during the April 13 altercation.

She declined to give a full statement at the scene, saying she would wait for an attorney.

In a separate case, Wisconsin police arrested 33-year-old Marckus L.A. Plaza on April 4 in connection with the fatal stabbing of his wife.

Piontek’s defense attorneys argue that she acted in self-defense during a domestic dispute.

In her 911 call, Piontek said she stabbed the man only after he “came at” her aggressively.

The defense has also said Piontek had previously experienced abuse by her fiancé.

A judge later set another hearing for Aug. 17. No trial date has been announced.

Piontek remains in the Brown County Jail on a $1 million cash bond.

The case is still active, and prosecutors will likely continue to argue that the fatal stabbing was intentional, while the defense is expected to keep pressing the claim that she acted out of fear during a violent domestic dispute.

As the case moves forward, the court is expected to consider the 911 call, witness accounts, physical evidence, and defense arguments about what occurred inside the home.