SPRINGFIELD, Mo. -- Many want to know how a Springfield woman, Diane Staudte, and her daughter Rachel, managed to kill not one but two family members by poisoning them.
The deaths happened months apart and the two were busted only after an anonymous tip alerted police to the fact that something strange was happening to Staudte's other daughter Sarah, who was fighting for her life in an Intensive Care Unit.
By their own admission, the mother and daughter carefully researched how to methodically poison their family members without being caught.
In the case of Diane Stoudte, police were called twice, months apart, to her home for a dead family member. But, there's a catch.
"The family moved between the first incident with the father and the second incident with the son Shaun, so there were two different addresses," says Lt. Tad Peters with the Springfield Police Department.
Officers went to Staudte's home on West Page where her husband died and then to another family home on West Swan, where her son died five months later.
While police dispatchers routinely help street officers with a history of calls to a particular address, if a person is the common link in a case it requires further investigation and suspicion a crime was committed.
"It's not something that's going to automatically pop up and say, 'you know, we had another death investigation involving this family.' You can do a search by name, of course, and see any past events with someone involving that name," adds Lt. Peters. "But, I don't know if that was done in this case because there was no indication at the second crime scene that it was tied to anything else."
Police didn't see any trauma to the body. A medical examiner ruled the deaths were because of natural causes without autopsy.
"It's hard to see that poisoning is involved."
And that's what Diane Staudte and her daughter Rachel were banking on. They researched the use of antifreeze as a poisoning agent. It's something pharmacist Terry Bark says can be easily mixed in a drink and undetected by the intended target.
"Certainly with a chronic ingestion, as opposed to an acute injection, the patient may be totally unaware or the person may be totally unaware of it."
Springfield Police say their investigation went as it should have.
"If they do that initial assessment and they don't see anything that catches their attention or that seems out of the ordinary, then they would just go ahead and document what they see and they'll also contact the medical examiner's office," says Lt. Peters. "In most cases they send someone out as well also looking for those suspicious signs. Even look back at it now the signs simply were not there, if you look at the first and the second case."
The case was reviewed by a supervisor of the violent crimes unit at the police department. And the medical examiner's officer ruled both the father and then the son died of natural causes. Not every person that dies goes in for a full autopsy.
KOLR10 News spoke to the medical examiner's office Monday. A spokesperson says they followed the policies of the office and clearly did not believe at the time these deaths were suspicious.