Police are used to dealing with people on the worst days of their lives. This day was different.

Computer scientist Troy Goldschmidt enlisted members of Wisconsin's Eau Claire Police Department for a marriage proposal on a cold November afternoon. 

The couple had a "very positive" prior interaction with Officer Maggie Andersen, according to the Eau Claire Police Department's public information officer, Josh Miller, when Moriah Prichard lost her cellphone on an earlier trip to the city.

So, Goldschmidt asked for Andersen specifically to be involved in the scheme, Miller said in a statement.

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The next time they were in town, about 90 miles east of Minneapolis, Goldschmidt and Miller coordinated the stop. 

The couple had just arrived and pulled over at an intersection before they'd even checked into their hotel.

"Is this like recently issued or anything?" an officer asks, after pretending to run Goldschmidt's license.

"I mean I got the new ID thing," Goldschmidt replied with a slight smirk Prichard couldn't see at the time.

The officer asked him to get out of the car. Once they're out of earshot, he whispers, "You all set?"

The clip cuts to Andersen's bodycam as she knocks on the passenger-side window, speaking with Prichard. She escorts her out of the car as well, as her partner pretends to put Goldschmidt's hands behind his back over a supposed issue with his license.

But he pulls out a ring, drops down to one knee and holds out his hand.

"Moriah," he said, as she turns around. "I love you so much. You're my best friend. I want to spend the rest of my life with you."

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Then he popped the question.

She said yes.

In a Facebook post, he thanked police for preserving the moment on bodycam.

"I'm glad you had the video because I barely remember what I said," he wrote. "Neither Moriah and I have been able to stop smiling!"

Prichard wrote separately that while she doesn't post much on social media, she had to post about her big moment.

"Thank you SO much Eau Claire Police Department for volunteering your time, and Troy Goldschmidt for your love, care and creativity," she wrote. "I couldn't be happier, and I can't WAIT to spend the rest of my life with you!"

In a statement, city police said it was their pleasure.

"You never know what's going to happen on a traffic stop," Eau Claire Police wrote on Facebook when they posted the video, accompanied by a wedding ring emoji.

Fox News' Mitch Picasso contributed to this report.