The Heitzigs do not have an answer right now, and may never get one.
Last week, their 12-year-old daughter Grace died unexpectedly during the night.
She was fine the night before, not sick, and generally was a healthy young Maple Grove High School student, outside of one seizure that happened last summer, her parents Charlie and Katie Heitzig told FOX 9.
But last Tuesday morning, when Katie Heitzig went into her daughter's room, she found her rolled up in a blanket on the floor, unresponsive, she explained to WCCO.
An autopsy did not determine a reason for her death (such as an unknown medical condition), or whether the lone seizure is connected.
In an obituary in the Star Tribune, Grace is remembered as someone not afraid to try things; playing different instruments, participating in different sports, testing recipes or getting involved in school clubs.
"She leaves a legacy of bringing joy, sunshine and giggles to all who knew her," it says on her Book of Memories page. "She did not just live her life as if her glass was half full but instead it was overflowing with hope and possibilities. She will continue to live among us but we will need to adjust our way of viewing her."
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Grace would have turned 13 on Friday, and students are encouraging one another to wear purple that day in her memory.