Donald Mayer, a 51-year-old White/Caucasian male, was found dead inside his family’s home on Cider Hills Drive in the Village of Waukesha on February 28, 2025. Although February 28 became the date publicly associated with the case because that was when authorities discovered him, investigators later determined that Mayer had actually been shot and killed on February 11, more than two weeks earlier. His wife, Tatiana Casap, was also found dead inside the residence.
The discovery followed a welfare check requested after Mayer’s mother became alarmed because she had not heard from the family and Waukesha West High School reported that Tatiana’s son, Nikita Casap, had been absent from school for an unusual length of time.
Deputies entered the residence and initially discovered Tatiana in a hallway, covered with blankets and towels and showing signs of decomposition. During a further search, they found Mayer in a first-floor office, concealed beneath clothing, blankets and other items. Investigators observed an obvious wound to the back of his head, and later testimony described the injury as appearing to be a gunshot wound. A receipt showed that Mayer had purchased a Smith & Wesson. 357 Magnum revolver, but the firearm was missing from the house.
The circumstances surrounding Mayer’s apparent absence had already begun to raise suspicions. Family members reported receiving strange text messages from his phone, while his employer said messages had been sent claiming that he was sick and unable to speak by telephone. Investigators later alleged that Nikita Casap had been using Mayer’s phone and identity to create the appearance that Mayer remained alive after the killings. Authorities also learned that a vacation hold had been placed on the household’s mail. Surveillance footage, cellphone information, financial records and witness statements were eventually used to reconstruct the period following the deaths.
By the time deputies discovered the bodies, Nikita and Mayer’s Volkswagen Atlas were gone, along with the family dog. Authorities traced Nikita’s movements westward through several states. He was ultimately stopped by police in WaKeeney, Kansas, while driving Mayer’s vehicle. Inside were the dog and property belonging to the family, including identification documents, ammunition and a Smith & Wesson. 357 Magnum firearm consistent with the weapon Mayer had purchased. Nikita was initially arrested and charged in Wisconsin with taking the vehicle without the owner’s consent and theft involving the firearm while investigators continued building the homicide case.
Prosecutors subsequently charged Nikita Casap with two counts of first-degree intentional homicide, accusing him of deliberately shooting Mayer and Tatiana inside the Waukesha home. Additional felony charges included hiding the bodies, theft and identity-related offenses. Investigators said a school acquaintance told detectives that Nikita had discussed killing his parents before the deaths. Prosecutors also alleged that after the shootings he remained in the house with the bodies for roughly two weeks, used his parents’ financial resources and communications, and eventually fled Wisconsin with cash, valuables, passports, Mayer’s vehicle, the firearm and the family dog.
The investigation eventually expanded well beyond the killings themselves. Federal investigators alleged that evidence recovered from Nikita’s electronic devices showed he had become involved with extremist material and was communicating about a plan to assassinate President Donald Trump and cause broader political violence. Authorities said the murders appeared to have provided him with money and freedom to pursue that plan, including discussions involving a drone and explosives and plans to travel to Ukraine. Those allegations became an important part of the prosecution’s account of motive, although Nikita was not federally charged for carrying out the alleged assassination plot.
The criminal case did not ultimately proceed to a murder trial. On January 8, 2026, Nikita Casap pleaded guilty in Waukesha County Circuit Court to two counts of first-degree intentional homicide, formally accepting responsibility for killing Mayer and Tatiana. Under the plea agreement, prosecutors dismissed seven remaining charges, including counts involving concealment of the bodies and theft. Each homicide conviction carried a mandatory life sentence.
On March 5, 2026, Judge Ralph Ramirez sentenced Casap to life imprisonment without the possibility of release. During the sentencing hearing, Casap acknowledged that his actions were wrong and expressed remorse, while prosecutors argued that the circumstances of the killings and the evidence of his subsequent plans demonstrated an extraordinary continuing danger. The defense sought the possibility of release after a lengthy period of imprisonment, but the judge declined to make him eligible for extended supervision. The sentence permanently resolved the question of criminal responsibility for Donald Mayer’s killing: his stepson had pleaded guilty to intentionally shooting him and was ordered to spend the remainder of his life in prison.
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