A 52-year-old northwestern Minnesota man was sentenced to 15 years in prison for leaving his own picnic drunk and crashing his speeding car, killing two sisters riding with him as he “showed off” his new wheels on a dark country road.

Along with his time in prison after pleading guilty to two counts of criminal-vehicular homicide, James G. Yahnke was sentenced Wednesday to 10 years’ probation in the crash about 35 miles south of Grand Forks that killed Teja R. Beyer, 21, and Mercedes D. Rowley, 23.

The sisters were at a picnic on May 17 hosted by Yahnke at his Nielsville home for co-workers, said his brother, Robert Yahnke. Beyer and Yahnke both worked in Crookston, Minn., at a bus manufacturing company.

James Yahnke’s son called the sisters’ family afterward and said his father took the women for a ride that night “to show off his new car” and then crashed on Traill County Road 17, said Debbie Mickelson, the sisters’ aunt.

The Highway Patrol said Yahnke was suspected of being drunk as he headed west in his 2014 Dodge Challenger at more than 90 miles per hour, veered into a ditch and struck an approach to a driveway. The car then rolled and hit a second approach.

Yahnke’s driving history in Minnesota includes two drunken-driving convictions in the late 1990s, according to court records.

Both women were thrown from the vehicle, the patrol added, suggesting that neither had on their seat belts or weren’t properly belted in.

A family member said the two women were living together in Grand Forks and helping each other raise their children.

Rowley worked at a nursing home in Crookston and left behind two children under age 3, and Beyer gave birth to her only child five months before the crash, according to the relative.