Rachel Staudte, 22, of Springfield was charged Saturday in the deaths of her father, Mark Staudte, and brother Shawn Staudte, and with attempting to harm a sister, Sarah, the Springfield News-Leader reported. The charges came a day after her mother, Diane Staudte, 50, also of Springfield, was charged with the same crimes.
The Greene County prosecuting attorney's office said the poisonings allegedly occurred between April 8, 2012, and June 12, 2013.
The charges came after police received an anonymous call June 11 that Diane Staudte was possibly responsible for "two or three homicides," the newspaper said.
The prosecutors office said Diane Staudte first told police she had acted alone, but after Rachel Staudte also allegedly confessed to her involvement, the mother admitted that she and her daughter had planned, researched and committed the crimes together, the prosecutors' statement said.
"Eventually, she admitted that she used antifreeze to poison them all," the probable cause statement said of Diane Staudte's alleged confession. "She admitted that she researched the use of antifreeze as a poison on the Internet."
She allegedly said she put antifreeze in her husband's Gatorade because she hated him and did the same to her son's Coke because he was "worse than a pest." She said she tried to kill her daughter because she didn't have a job and had student loans that had to be paid, the statement said.
2014: The Year in Music [PHOTOS]