Plummer said she and her classmates formed a quick bond with Heiser, spending countless hours studying macroeconomics together.
"We really got to know each other through school, and that was really nice, because she was really someone to talk to," Plummer said.
Many of Heiser's classmates are in shock over what happened and have come together to remember her and show support for the family.
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"Everyone's pretty just shocked,” Plummer said. “A lot of people knew her, and a lot of people have similar stories as me: 'She was in my class,' 'Oh, I sat next to her,' or 'She was my first friend freshman year.' It was a lot of those stories of people coming out and really showing their support for her family and friends.”
Jennifer Sirons served as chief financial officer for Clark County Juvenile Court since 2011.
“Jen was not only a very gifted and devoted employee here at the court, she was also a very sweet friend to many of us,” Juvenile Court Judge Robert Vaughn said in a statement.
“We are all heartbroken, and we grieve deeply for her family. We ask that the public join us in praying for her daughters and extended family for the terrible loss and pain they are experiencing,” Judge Vaughn said.
>>Springfield murder-suicide: couple going through a divorce
Eric Sirons’s son, Andrew, admitted the couple's relationship had deteriorated, but that the father he knew was not a bad person.
"People kind of have a negative view on him right now...but he was a really good man, he would do anything for anybody, if they needed help, he would drop what he was doing and come help," Andrew Sirons told News Center 7’s Sean Cudahy on Wednesday evening.
Springfield Chief Lee Graf said the investigation has determined the incident was murder-suicide. Police have not released any details about what happened in the house leading up to the shooting. The investigation is continuing, he said.