A Minnesota man will have to spend the weekend closest to Feb. 19 in jail every year for the next 10 years for running over and killing an 85-year-old woman whom he didn't see because his windshield was frosted over.

Robert John Tofstad, 21, of Minnesota City was sentenced to 60 days in jail and 400 hours of community service — plus the unusual annual incarceration — in a plea agreement reached in August but not filed until this month in Third Circuit Court in Rochester.

Police said Tofstad, then 19, was trying to drive by hanging his head out the driver's side window of his 1998 Saturn when he struck Ruth Doris Brendel on the morning of Feb. 19, 2012, as she was walking to church in Winona. Brendel died later that day.

Police said Tofstad was driving directly into the morning sun with the car's windshield and side windows frosted over. Weather records show that the low temperature that day was 14 degrees.

Tofstad told investigators that he had had a few drinks the previous night, and officers found suspected marijuana debris and four unopened beers in his car. The drinking age in Minnesota is 21.

In exchange for Tofstad's guilty plea to vehicular manslaughter, prosecutors dropped other charges of careless driving and underage DUI. As part of the agreement, Tofstad will be on probation for 10 years, during which he will have to check into jail over the weekend closest to the anniversary of Brendel's death.

Tofstad is also barred from consuming alcohol and will be subject to random testing for the 10 years of his probation.

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