MOORHEAD - It's been two years since Ray Kvalvog lost his two teenage sons in a crash as they traveled along Interstate 94 to a basketball tournament.

"I remember dropping them off at the school parking lot. Less than an hour later, they're dead," Kvalvog said as a guest on WDAY radio Friday, June 23. "I can't get it out of my mind seeing my boys dead and in the morgue. It doesn't get better."

Kvalog announced to radio listeners that he's doubling the reward he's offering to $100,000 for information related to the driver of a semi believed to have encroached on the boys' lane before they crashed on June 23, 2015, near Dalton, Minn.

Zach Kvalvog, 18, was driving 14-year-old brother, Connor, and two teammates from Park Christian, a Moorhead private school they all attended, to a tournament in Wisconsin. When the semi veered into Zach Kvalvog's lane, it caused him to swerve out of the way and overcorrect, a Minnesota State Patrol crash report said. The semi did not stop after the crash.

The Dodge Ram 2500 pickup truck Zach Kvalvog was driving rolled into the median and ended up on the interstate's westbound lanes. The brothers died in the crash. Passengers Mark Schwandt and Jimmy Morton were hospitalized, but they recovered.

Following the crash, Ray Kvalvog filed a wrongful death lawsuit against Park Christian, basketball coach Josh Lee, the automaker and insurance company.

Ray Kvalog said they don't blame Park Christian or any individual. He said the suit is not an "indictment of the school" or an opportunity to make money. The family is financially sound, but they want to know how this could happen to their sons, he said.

"The question that always comes up: 'Why can't you move on?' That is so devastating to my wife and I because the answer to move on to what? What is there to move on to? Our boys were our whole life, they were everything."

He said if Zach were still here, he would likely be playing basketball at North Dakota State University - wishful thinking would have his son a track star, too. Connor would be taking over his brother's spot at Park Christian.

Kvalog said Connor always joked with Zach that he was, "Going to take all your records away," and he admits, with bias, his youngest was "Big Ten material."

"The boys were just at a time in their life, 'the fun stage,' full of life, in every activity," he said. "Then all of a sudden it's gone."

Kvalog said the lesson for school districts to avoid having something like this happen again is to look carefully at how they transport students. He said the crash site would also benefit from yellow signs with arrows to indicate a slight curve and give drivers a chance to slow down.

A billboard along the interstate still asks for the public's help in finding closure. Kvalvog said anyone can call (701) 793-0187 if they have any information about the fatal crash.