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Driver in fatal Big Lake collision with ATV indicted for criminally negligent homicide

  • Author: Zaz Hollander
  • Updated: July 7, 2016
  • Published July 1, 2014

PALMER -- A Palmer grand jury has indicted a 24-year-old Wasilla woman on charges of criminally negligent homicide for a collision last year that killed a 25-year-old Big Lake man riding a four-wheeler.

The grand jury also indicted Sierra M. Mahnke on charges of driving under the influence.

Mahnke had morphine and oxycodone in her system at the time of the collision, according to a sworn affidavit filed by an Alaska State Trooper earlier this year.

She was arrested at 1:15 a.m. Saturday in Wasilla after the grand jury last week handed up the two indictments -- both charges linked to the death of Caleb Younger in November.

Mahnke entered a not-guilty plea during a court appearance Monday, according to a report from the hearing. As of Tuesday, she remained jailed at Mat-Su Pretrial Facility on $10,000 cash/corporate bail.

The fatal accident happened around 10:30 p.m. Nov. 23. Mahnke was driving a 1995 Ford Taurus sedan south on Big Lake Road near Birch Lake Drive when she hit a Yamaha ATV traveling in the same direction on the road, according to an affidavit filed in March by trooper Daniel Sadloske. It's illegal to drive an off-highway vehicle along a road.

The ATV turned in front of the car, a troopers spokeswoman said at the time. Younger wasn't wearing a helmet.

He was pronounced dead at the scene of the collision. Mahnke wasn't hurt.

Troopers got a search warrant to draw Mahnke's blood at Mat-Su Regional Medical Center within four hours of the collision, according to Sadloske's affidavit. A toxicology report from the Washington State Patrol Crime Lab found both morphine and oxycodone at levels of ".017% mL (milliliters)" at the time of the collision.

The numbers may or may not figure into Mahnke's court proceedings.

Alaska statute provides a blood level at which alcohol is shown to impair driving -- .08 blood alcohol -- but there aren't enough studies to establish a threshold for prescription drugs, according to John Skidmore, head of the Alaska Department of Law's criminal division.

Instead, statute defines driving under the influence as when someone is "impaired" by alcohol, an inhalant or a controlled substance.

Generally, prosecutors screen DUI cases involving prescription drugs by considering factors including whether the defendant had a prescription, a doctor's analysis of their blood levels and whether there's evidence of poor driving, said Skidmore, who said he is not familiar with this particular case.

Mahnke was charged with felony drug possession in February in a separate case. She tried to hide methamphetamine during a Parks Highway traffic stop, according to an online troopers report.

She herself was the victim of a serious car accident when she was 17. She was badly injured as a passenger in a rollover outside Wasilla in 2008, according to troopers reports at the time.

Mahnke told her graduating class at Burchell High School in 2011 that she dropped out at 16 and then took several years to overcome the injuries inflicted by the accident before persevering to finish high school, The Mat-Su Valley Frontiersman reported that year.

"I'm now in my 20s and I'm finally getting my diploma," she told the crowd.

Reach Zaz Hollander at


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