Noah Pozner was among the first children buried after the Dec. 14, 2012, shooting at Sandy Hook Elementary School in Newtown, Conn., which killed 20 first graders and six educators. Noah hid with 15 classmates in the classroom bathroom, a 4½ by 3½-foot space into which the gunman fired more than 80 rounds from a Bushmaster semiautomatic rifle, killing all but one child.

Bullets tore through Noah’s back, arm, hand and face, destroying most of his jaw. Mr. Pozner and Noah’s mother, Veronique De La Rosa, held a private, open-coffin viewing before his funeral service, which was attended by Dannel Malloy, Connecticut’s governor at the time. When Mr. Malloy arrived, Ms. De La Rosa took him by the hand to see her son, lying in a mahogany coffin in a room at the back of a funeral home in Fairfield, Conn.

“I’m thinking to myself, ‘I’m going to pass out. She’s going to show me open wounds and I’m not going to handle it very well,’” Mr. Malloy said in an interview for my book “Sandy Hook: An American Tragedy and the Battle for Truth.”

The damage to Noah’s mouth was hidden by a square of white fabric, so Mr. Malloy was not shown raw wounds. “I wouldn’t have taken it to that level,” Ms. De La Rosa said. But the governor “was still looking at a dead child,” she said. “A child who practically the day before had been running around like a little locomotive, full of life.”