The driver of a tour bus carrying 42 people involved in a massive crash on the Seward Highway, which left one person dead, has been indicted on charges of criminally negligent homicide.

Alaska State Troopers said Friday that a grand jury had also indicted 63-year-old Charles Curtis on 11 counts of assault in connection with the July 31, 2015 crash. John Zollner III, 55, was killed during the six-vehicle wreck.

Troopers said at the time of the crash that Curtis’s Premier Alaska Tours bus had rear-ended a truck stopped northbound in a line of three vehicles making a left turn into the Alaska Wildlife Conservation Center. The bus then swerved into the oncoming lane, striking a GMC Yukon driven by Zollner; he died at the scene. At least three people were critically injured, and Curtis was taken to a hospital by a ground ambulance.

Jessica Cowgill, a nearby nurse who was among the first responders, said at the time that she and others had immediately bandaged wounds, given intravenous fluids and comforting survivors in the wake of the crash.

"Just sitting and talking with them, calming them down, supplemental oxygen -- that's what we did," Cowgill said.

The wreck was among several high-profile crashes on the Seward which prompted discussion between troopers and Anchorage police over who would patrol the highway’s densely trafficked section north of the Kenai Peninsula, which police began to cover last fall.

Troopers spokeswoman Megan Peters said in an email that the circumstances of the crash made it suspicious to troopers "from the beginning." Investigators declined to answer questions about whether Curtis was impaired or distracted during the crash or why it took nearly three years to file charges.

"The bus rear-ended a vehicle in the same lane of travel that was stopped waiting for another vehicle to turn," Peters wrote.

Peters said the assault charges included two counts of second-degree assault for Zollner's wife, Amy Zollner, and her daughter Elko Benefield who were injured in the same vehicle with him. Nine additional counts of fourth-degree assault were charged in connection with "other people injured during the incident."

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