INDEPENDENCE, Mo. -- Nearly a year after a grandfather and granddaughter were killed while they were training for a charity bike ride, the trial for a man police said was responsible for their deaths got under way.

William K. Johnson's eyes were hidden behind dark sunglasses in the Jackson County courtroom where the trial began Tuesday.

Prosecutors charged Johnson, 49, of Grandview, Mo., with involuntary manslaughter in connection with the deaths of Larry Gaunt, 59, and his 14-year-old granddaughter, Sierra Gaunt.

The two were cycling on Raytown Road last August when they were struck and killed by Johnson's pickup.

Prosecutors argued that Johnson could have avoided hitting both cyclists.

One of their witnesses was a Grandview police accident reconstruction officer who said that the grandfather and granddaughter were heading the same direction as Johnson's pickup. That officer said Johnson veered off the road, and when he tried to get back on the road, he overcorrected.

Defense attorneys argued that Johnson could not have avoided them because the two cyclists pulled out in front of him. Lester Dickey, a family friend, said he could not understand why prosecutors filed a criminal charge against Johnson.

The Gaunt family declined to comment after hearing testimony Tuesday from several witnesses.