In 2012, tragedy struck the family of 61-year-old musician Mark Staudte in Springfield, Missouri. On 8/4/2012, Mark died unexpectedly. His wife, 50-year-old nurse Diane Staudte, told police he had been unwell for several days, eating less and sleeping more than usual. Bandmates noticed Mark exhibiting unusual behavior two nights prior, including slurred speech and a yellowish complexion. Diane also mentioned Mark had no history of seizures, but suffered three that evening, the last 45 minutes before she found him unresponsive. When asked why she didn't call 911, Diane claimed Mark didn't want to go to the hospital.

Police reports noted dried blood around Mark's mouth. His death was attributed to natural causes, partly due to his perceived unhealthy lifestyle. At the memorial service, attendees observed Diane's lack of grief for her husband of over 26 years.

Mark and Diane Staudte (top row) with their 4 children. Photo: *ABC*

An insurance payout allowed Diane to purchase a new home in a nicer area of Springfield. There, on 2/9/2012, just five months after Mark's death, Diane reported finding her eldest son, 26-year-old Shaun, dead on his bedroom floor. She told police that Shaun, who had autism, had experienced a seizure on 30/8 and had flu-like symptoms, including diarrhea, nausea, body aches, and headaches, for three weeks prior. She didn't seek medical attention because she believed he was hydrated.

Police found no significant injuries on Shaun, but did observe dried blood around his mouth. They received an anonymous tip implicating Diane, but the autopsy attributed Shaun's death to pre-existing health conditions.

On 9/6/2013, Diane rushed her 24-year-old daughter, Sarah, to the hospital. Doctors struggled to diagnose the cause of Sarah's kidney failure and brain hemorrhage.

On 11/6, police received an anonymous call. The tipster, later identified as the family's pastor, accused Diane of "two or three murders," referring to the deaths of Mark and Shaun, and Sarah's critical condition. On 13/6, at the hospital where Sarah was being treated, an investigator overheard Diane laughing with staff and discussing a planned trip to Florida the following week while her daughter fought for her life.

Sarah's doctor suspected poisoning, as no tests could explain her symptoms.

On 20/6/2013, Diane was interrogated by police. Initially denying involvement, she confessed to poisoning her husband and children with ethylene glycol, a component of antifreeze, which she mixed into Mark's sports drinks and Shaun and Sarah's soft drinks.

Forensic toxicologist and Associate Professor at the University of New Haven, Robert Powers, explained that testing for ethylene glycol isn't standard in autopsies. When examiners encounter a seemingly natural death, there's no reason to look for such specific substances.

Symptoms of ethylene glycol poisoning, such as nausea, vomiting, decreased alertness, and slurred speech, can mimic other illnesses, making diagnosis difficult. Diane's motives were chilling: she "hated" Mark, claiming he was abusive. She described Shaun as an "interference" and Sarah as a burden due to unemployment and student loans.

Diane Staudte during questioning at the Springfield Police Department, 2013. Photo: *Greene County Prosecuting Attorney's Office*

Diane didn't implicate anyone else, but a search of the Staudte home uncovered a journal belonging to her 22-year-old daughter, Rachel. An entry dated 13/6/2011 read: "It's sad when I realize how my dad is going to pass away within the next two months… Shaun, my brother will go soon after… It will be hard to get used to the changes but it will be okay." Rachel initially denied knowledge of her mother's crimes. However, on 22/6/2013, she confessed to her involvement, admitting to researching murder methods with her mother, but claimed to have opposed harming her siblings.

Rachel helped her mother research methods but argued against poisoning her siblings. "We argued so much about Shaun because I still thought we could put him in a home but she wanted him out of the way," Rachel told police. "Sarah was useless as well. We could find a place for her," she added. They eventually took Sarah to the hospital because Rachel "didn't want anyone else dying in the house." Rachel revealed their plan to eventually poison their 11-year-old sister, too. Powers noted that even if someone initially survives antifreeze poisoning, kidney failure can be fatal later on. Sarah miraculously recovered but suffered permanent neurological damage and now lives in an assisted living facility. The youngest Staudte daughter was placed in alternative care.

Diane Staudte during a prison interview, 2022. Photo: *ABC*

On 5/5/2015, Rachel pleaded guilty to two counts of second-degree murder and one count of first-degree assault in exchange for testifying against her mother. She received two life sentences in 3/2016, eligible for parole after 42.5 years. At her sentencing, Rachel apologized to Sarah for not being brave enough to do the right thing. In 1/2016, Diane entered an Alford plea to two counts of first-degree murder and one count of assault, acknowledging the prosecution had enough evidence to convict her while maintaining her innocence. She received three life sentences without parole in 2018. In a 2022 interview, Diane continued to claim innocence, suggesting her husband was involved with "dangerous people." However, no evidence supports her claims. Despite Diane's attempts to deflect responsibility, all evidence points to her and Rachel as the perpetrators of these horrific crimes.

Tue Anh (*AETV*, *ABC*)