A Phoenix jury found a man guilty of child abuse Wednesday for forcing his grandsons on two brutal hikes through the Grand Canyon in August.

Christopher Alan Carlson, 45, pushed, choked and kicked his three grandsons during hikes that lasted more than 15 miles

The oldest, age 12, testified that the hike was so strenuous he secretly asked a hiker to call 911 after he threw up and fell to the ground.

"I needed medical attention and I was hurting and he was hitting and pushing me and calling me fat," the boy said,. "I was scared and it was hard and I was all weak and tired and kind of hurt."

Prosecutors said the Indiana man didn't allow his grandsons, ages 12, 9 and 8 years old, to eat or drink water during the hikes on Aug. 15 and Aug. 28.