Even before she left the scene, Krista Sullivan knew what the evidence would reveal. She spotted the offenders' tracks, then rounded up the remains. It looked like an open and shut case.
Back at headquarters, she placed the proof on a slide, stained it with dye and studied it under a microscope.
Just as she suspected: Pollen. Everywhere.
After counting the number of grains on the slide, she plugged the total into a formula and reported a"very high level" pollen reading to the National Allergy Bureau.
Sullivan, 33, along with fellow allergy researcher Jenjira Skrei, 26, has been tasked with a special duty. As the only two certified pollen counters in the state, they track the amount and variety of pollen circulating in Minnesota's air — posting their findings on websites used by allergy doctors and scientists.
The two women, the keepers of the state's official pollen tally, are especially busy now that Minnesota is nose-deep in the spring allergy season.
While weather reports, websites and mobile apps provide allergy alerts, pollen counters like Sullivan and Skrei are a rare breed. They've undergone extensive training by the National Allergy Bureau, and have mastered the science of identifying the dizzying array of pollen grains as small as dust.
It's tedious work, but Skrei and Sullivan relish it. For them, discovering what exactly is causing so much misery for the millions with seasonal allergies makes every day feel like a whodunit.