An Indiana man has been indicted on six counts alleging child abuse stemming from rim-to-river-to-rim hikes in Grand Canyon National Park with his three grandsons during some of the hottest days of the summer.

The indictment was returned against Christopher Carlson, 45, on September 20 by a grand jury seated in Phoenix, according to agents who investigated the case. It alleged that Mr. Carlson exposed his three young grandchildren to "circumstances likely to produce death or serious bodily injury."

"The indictment alleges that Carlson took his three grandsons, ages 8, 9, and 12, on two separate hikes in the park in August when temperatures were in excess of 100 degrees and severely limited their water and food, marched and ran them up dangerous terrain, and placed their health at risk," a Park Service statement said.

“The indictment alleges that the defendant repeatedly denied food and water to his grandchildren, physically abused them, and placed them in harm's way," said acting U.S. Attorney Ann Birmingham Scheel.  "The children were rescued because of the quick action of park staff and concerned hikers on the same trail. Together, they prevented a tragic outcome."

A 24-page complaint a Park Service special agent filed against the Indianapolis man alleged numerous instances of physical and verbal abuse against the boys. Mr. Carlson, during his interview with rangers, denied commiting any physical abuse, the complaint noted.

The complaint submitted by Special Agent Christopher Smith was built around information provided by rangers who encountered and observed Mr. Carlson and the boys on the Bright Angel Trail on August 15 and August 28.

Rangers also were contacted by another hiker who encountered the four on the Bright Angel Trail on August 28. The caller told rangers that the boys "were hyperventilating and one of the children told the caller 'call the agency' or 'call the emergency,'" the complaint noted. "The description given by the caller matched Carlson and the boys."

Conviction on the charges carries a maximum penalty of life in prison, a $250,000 fine or both.