Diane Staudte was sentenced to life in prison without the possibility of parole in 2016, while Rachel Staudte pleaded guilty to second-degree murder in May 2015 as part of a plea deal in exchange for testifying against her mother at her trial, eventually being sentenced in March 2016 to life in prison with the possibility of parole.
The Staudte children had varying special needs, with Shaun being on the autism spectrum and still living at home, and the nine-year-old girl, then a fourth-grade student, having learning disabilities.
In addition, Sarah Staudte, a university graduate, had incurred a high amount of student loan debt and was also living at home with her parents.
Diane alleged that Mark was lazy, would throw objects when angry, and that by the point of killing him, she "hated his guts".
Both victims were found with a suspicious ring of blood around their mouths, but the deaths were not investigated any further, owing in part to Mark's lifestyle, which included alcohol consumption on a regular basis.
They had sneaked the substance into sports drinks that Mark regularly consumed, as well as into Shaun's favorite soda pop, and had specifically bought it online so as to ensure that there was no noticeable taste to it when hidden.
Rachel and Diane also admitted that the remaining daughter, the youngest, was to be poisoned after Sarah's death because of the burden of her learning disabilities.
Her mother, Diane Staudte, pleaded guilty to two counts of murder in January 2016 and was sentenced to life in prison without the possibility of parole.
[13] The public and media expressed disgust over Diane's favouritism towards Rachel, as well as her view of her disabled children as burdens.
Additionally, the case was discussed at length in multiple true crime YouTube videos, and featured in a segment of 20/20, where Sarah Staudte was interviewed in recovery from her poisoning.