It has now been four years since the body of University of Wisconsin-Madison student Brittany Zimmermann was found.
In a case that has yet to be solved, the 21-year-old was stabbed to death in her downtown Madison apartment.
To honor the anniversary, her parents, Kevin and Jean Zimmermann, hosted a free microchip clinic at the Humane Society of Portage County, near her hometown of Marshfield.
The Zimmermanns originally donated $1,500 to the Humane Society to cover the cost for people who wanted to get their pets microchipped, a process that enables lost or stolen pets to more easily be returned to their home.
They said it's a small gesture that they know would have made their daughter happy.
"She would be so proud. She would be smiling looking down," said Jean Zimmermann. "The day is beautiful. This would absolutely be something she would support 100 percent."
The turnout was so large that the Zimmermanns decided to increase their donation to $2,000.
Meanwhile, Zimmermann's death remains an open case with Madison police.