While Diane’s job as a healthcare worker was the main source of income, Mark stayed home to look after their four kids and also sang in a popular blues band.
‘He loved his family,’ bandmate and friend Charles Alexander told the TV program 20/20.
Life could be hard sometimes, though. Diane was exhausted by work and supporting Shaun, 26, who had autism, Sarah, 24, who was unemployed and their youngest daughter, Brianna, 11, all in a cramped three- bedroom home.
The only person Diane felt she could rely on was her middle daughter Rachel, 22.
A straight-A student and gifted artist, she was Diane’s golden child.
Then disaster struck the family.
On Easter Sunday 2012, Diane came home from the Redeemer Lutheran Church, where she was the organist, to find Mark dead. Not known to lead a healthy lifestyle, his death was ruled to be of natural causes.
During a memorial service for Mark, mourners noticed that Diane seemed surprisingly composed.
‘There was no sadness. I thought it was just her way of grieving,’ said Mark’s friend Rob Mancuso.
With the $20,000 life insurance Diane received from Mark’s death, she packed up and moved the kids to a bigger house in a better part of town. Hardly ve months had passed when Diane found herself at the centre of yet another tragedy when Shaun died suddenly, too.
When Diane informed a medical examiner that he’d suffered from regular seizures, they concluded he’d also died of natural causes.
But rather than grieving, Diane seemed to take the untimely deaths in her stride.
Don’t think I’ve seen mom so chilled out like this in a long time, Rachel posted on Facebook one month after her brother’s death.
When Diane’s eldest daughter, Sarah, went into hospital with organ failure, family friends weren’t sure how much more heartache the Staudtes could take. But then police got an anonymous tip-off saying that Diane had killed her husband and son, and was trying to kill her daughter.
It seemed absurd. Diane was a loving wife and mother. Besides, why would she want to wipe out her family?
Alarmed by the tip-off, Detective Neal McAmis looked into Mark and Shaun’s deaths.
Going to visit Sarah, who was critically ill in hospital, he spoke to a nurse who said Diane had been behaving strangely. She’d joked about her daughter’s condition and even mentioned an upcoming holiday to Florida.
Then a doctor told the detective that Sarah’s illness could be a possible case of poisoning.
Armed with this information, he called Diane in for questioning and the truth came tumbling out. She’d poisoned her own husband and two children.
Diane was arrested and Detective McAmis gently informed Rachel that her mother was a murderer. Meanwhile, the Staudte family home was searched for evidence. Rachel’s purple diary had a startling entry dated before her father died.
'It’s sad when I realise how my father will pass on in the next two months', she wrote. 'Shaun, my brother, will move on shortly after.
'It will be tough getting used to the changes, but everything will work out.'
It was a truly shocking revelation. Rachel was in on it. The mum and daughter had hatched the evil plot to kill together. After researching how best to do it, they’d put antifreeze in Mark’s sports drinks.
‘I hated his guts,’ Diane confessed. ‘I guess I’d just had enough.’
With Mark out of the way, Diane considered her son to be a burden and lazy.
‘He was more than a bother... more than a pest,’ Diane said.
Once again, soft-drink bottles had been laced with antifreeze and Shaun suffered the same fate as his father. But Diane still wasn’t finished. In her confession, Rachel explained that Diane found Sarah to be another annoyance. Recently graduated from college, according to Diane, she wasn’t getting a job quick enough to pay off her student debts.
‘Both Shaun and Sarah would just... trash the house. Never helped support, or even contribute,’ Diane said. So the pair then poisoned Sarah, too. When Sarah became ill, Diane and Rachel took her to the emergency room, but it wasn’t out of guilt.
‘I didn’t want another one to die in the house. Houses are nasty after somebody’s died in it,’ Rachel explained.
And the mother and daughter almost got away with it. But then the family’s pastor became suspicious of Diane’s lack of emotion and tipped off police.
Sarah survived, albeit with permanent brain damage. After learning to walk and talk again, she was able to sit in the front row during the trials where Diane and Rachel Staudte both pleaded guilty to two counts of murder.
Rachel testified against her mother and was sentenced to two life terms with a non-parole period of 42 years and six months. In January 2016, Diane was sentenced to life in prison without parole.
Diane’s youngest daughter was placed in foster care. In her victim impact statement at her mother’s trial, Sarah stated, ‘She not only took away my dad and brother, she took away my independence.’
Now in an assisted-living home, Sarah’s strength shines through.
‘I prefer to be a survivor than a victim,’ she said.
This article appeared in this week's issue of that's life.