The Staudte Family: The Antifreeze Murders (Part 2)

An Investigation Ensues (Finally)

  • June 11, an anonymous tip came to police accusing Diane of being responsible for 2-3 homicides (1)
  • June 13, an investigator comes to the hospital where Sarah is being treated
    • He heard about some of the things Diane had been saying, like talking about her vacation while her daughter is literally fighting for her life and he agreed that was strange
  • The doctor overseeing Sarah’s case speculated that she may have been poisoned because from all the tests they had run with no affirming results, he couldn’t think of anything else that would explain her symptoms

The Confession

  • June 20, Diane was interviewed by police
    • She initially denied everything but eventually admitted she’d poisoned all three of them with antifreeze.  Any guesses?
  • She had mixed the antifreeze into Mark’s sports drinks and sodas for Shaun and Sarah


An Accomplice?

So far there’s been nothing to indicate that Diane wasn’t working alone, right?

A search of the Staudte home had some unexpected results… a journal was found that said things like “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.”

Whose Journal Was It?

  • The journal referred to Mark as “my father” so it couldn’t have been Diane’s
  • 22 year old Rachel who had originally told police she knew nothing about the murders confessed after confronted with the journal
  • She said “Mom brought it up and we discussed”


  • Rachel claimed she had helped her mother research killing methods and it sounds like she was pretty on board with killing Mark (1)
    • She didn’t personally have a problem with her dad but wanted to help relieve her mother’s stress and unhappiness
  • She said that she objected to poisoning her siblings though
  • They argued a lot about Shaun as she felt like they could take him to an assisted living facility
  • Similarly, she didn’t feel killing Sarah was necessary as they could have simply made her find somewhere else to live
    • They thought she was lazy. She wasn’t making an effort to get a job. She sat around watching YouTube videos without lifting a finger around the house.
    • Rachel also said she was “very nosy”
    • They only took Sarah to the hospital because Rachel “didn’t want another one to die in the house”
  • She also admitted that they had planned to eventually kill Brianna as well
    • Diane had a different story (2)

Rachel Makes a Deal

  • Rachel made a deal with the prosecutors to testify against her mother and pled guilty to 2 counts of second degree murder as well as one count of first degree assault
  • In exchange for her testimony and confession, she was given two life sentences in March 2016, with eligibility for parole in 42.5 years
  • She is now incarcerated in the Women’s Eastern Reception Diagnostic and Correctional Center in Vandalia, Missouri.
  • At her sentencing, she said to Sarah, “I’m sorry I couldn’t find the courage to stand up for what was right, to go for help, to protect you and our siblings,” Rachel said. “Your suffering could have been prevented and I hate myself for not being there for you…. I want you to know that you are an inspiration to me.


  • Diane pled guilty to two counts of first-degree murder and one count of assault through an Alford Plea
  • An Alford plea is “a type of guilty plea in which the defendant does not admit to committing the crime but agrees that the prosecution has enough evidence to obtain a conviction. This type of plea allows the defendant to plead guilty but maintain their innocence in the eyes of the law.”
  • She was sentence to 3 life terms with no possibility of parole and is incarcerated at the Chillicothe Correctional Center in Missouri
  • In a 2022 interview with 20/20, Diane suggested she was in fact NOT guilty. She said Mark had “people that are very dangerous” in his life and “somebody probably came in and gave him something.”



  • Sarah faced both her mother and sister at their sentencings
    • She said she prefers to be a survivor than a victim
  • She lives in an assisted care facility and has a state appointed guardian
  • She’s embraced her spirituality and is a devout Christian
  • In an interview with ABC News, she said that while her mother and sister took away her livelihood and independence, they did not take away her desire to fulfill her future dreams (1)
  • She says she’s no longer angry at her mother and sister said “I forgive them for what the did because forgiveness is the right thing to do”

Video Mom who confessed to fatally poisoning husband, son ‘can’t tell’ if she’s guilty – ABC News


Brianna was placed in foster care


All sources accessed August, 2023:

How Diane and Rachel Staudte Killed Their Family With Antifreeze

Mom, Daughter Describe Killing Family Members With Anti-Freeze in Never-Before-Seen Interrogation Tapes

Mother convicted of poisoning her family maintains her innocence

Just the Two of Us

What Is An Alford Plea in Relation to Criminal Proceedings,the%20eyes%20of%20the%20law.’

Missouri Woman Recalls Moment She Suspected Her Mom Tried to Kill Her