Title: A Deadly Family Pact: How Diane and Rachel Staudte Used Antifreeze to Eliminate Their Own
By the summer of 2013, the Staudte family of Springfield, Missouri, seemed plagued by misfortune. First, Mark Staudte, a father of four, died suddenly in April 2012. Then, just months later, his 26-year-old autistic son, Shaun, also met an untimely demise. And when their daughter, Sarah, was rushed to the hospital in June 2013 with failing organs, it seemed tragedy had struck once again.
But this was no cruel twist of fate—this was murder. A sinister plot orchestrated not by a stranger, but by the people Sarah trusted most: her own mother, Diane, and her sister, Rachel.
Murder in Plain Sight
When Mark, 61, passed away in April 2012, Diane, 50 at the time, told authorities he had been feeling unwell but had refused medical treatment. Given Mark’s history of poor health, his death was ruled natural. There was no reason to suspect otherwise.
Diane, however, showed little emotion at his memorial service. Soon after, she collected his life insurance payout and moved into a nicer home in Springfield. Less than five months later, on September 2, 2012, she reported finding her son, Shaun, dead in his bedroom. Again, she claimed he had been sick and suffered from seizures. An autopsy found nothing suspicious.
No one had any idea that Diane had already gotten away with two murders.
A Suspicious Tip
The family’s pastor, however, wasn’t convinced. After Diane’s 24-year-old daughter, Sarah, was hospitalized in June 2013, barely clinging to life, the pastor placed an anonymous call to the police. He suspected Diane had something to do with the deaths of her husband and son—and now, possibly Sarah’s deteriorating condition.
Investigators took the tip seriously. When they visited the hospital, they found Diane behaving oddly. Rather than showing concern for her critically ill daughter, she was chatting about an upcoming vacation.
Doctors treating Sarah were perplexed—nothing they tested for could explain her sudden kidney failure and brain hemorrhaging. But when investigators mentioned the possibility of poisoning, a chilling realization set in: Sarah had likely been fed antifreeze.
The Deadly Confession
On June 20, 2013, police brought Diane in for questioning. At first, she denied any wrongdoing. But under pressure, she finally broke. She confessed to slipping antifreeze into Mark’s sports drinks, and into sodas for Shaun and Sarah.
Her reasoning? “I hated [Mark’s] guts,” she admitted. She claimed he was abusive and had thrown things at her and the kids. As for her autistic son, Shaun, she coldly dismissed him as “more than a pest.”
Sarah’s fate had been sealed simply because she was unemployed and had student loans.
A Chilling Accomplice
Diane had acted alone—or so it seemed. But when police searched the family home, they uncovered a disturbing journal entry from Rachel, Diane’s 22-year-old middle daughter.
“It’s sad when I realized how my father will pass on in the next two months… Shaun, my brother, will move on shortly after… It will be tough getting used to the changes, but everything will work out.”
Brought in for questioning, Rachel initially played innocent. But faced with mounting evidence, she crumbled.
“Mom brought it up, and then we discussed,” she admitted. Rachel had helped her mother research different poisoning methods. But even she hesitated when it came to her siblings. “Shaun, we argued about a lot because I still think we could have put him in an assisted living [facility], but she wanted him out.”
And Sarah? “She was equally unneeded,” Rachel said, emotionless.
Diane and Rachel had only taken Sarah to the hospital because Rachel “didn’t want another one to die in the house.” But even more disturbing was the fact that the pair had planned to kill their youngest family member—an 11-year-old girl—next.
Where Are They Now?
Sarah miraculously survived but suffered permanent neurological damage. She now lives in an assisted-living facility. The youngest Staudte daughter was placed into foster care.
Diane and Rachel were sentenced to life in prison in 2016. Rachel, after accepting a plea deal, was given two life sentences with eligibility for parole in 42.5 years. She is incarcerated at the Women’s Eastern Reception Diagnostic and Correctional Center in Missouri. At her sentencing, she turned to Sarah and tearfully apologized: “I’m sorry I couldn’t find the courage to stand up for what was right.”
Diane pleaded guilty to two counts of first-degree murder and one count of assault. Under an Alford plea, she maintained her innocence while acknowledging there was enough evidence to convict her. She received three life sentences with no chance of parole and is serving time at the Chillicothe Correctional Center in Missouri.
A Twisted Denial
Despite her detailed confession, Diane has since attempted to rewrite history. In a 2022 interview with 20/20, she bizarrely claimed her husband had “dangerous people” in his life who must have poisoned him. She refused to take responsibility, even after admitting to the crimes years earlier.
Forensic psychologist Dr. Rod Hoevet summed up the case: “That a mother would kill her own family is already shocking… but that she convinced her daughter to help? That’s nearly unheard of.”
Diane and Rachel Staudte weren’t just mother and daughter. They were partners in murder—destroying their own family, one poisoned drink at a time.
