The child then went on a killing spree, bashing three lizards to death with a rock, including the zoo's beloved, 20-year-old goanna, which he then fed to "Terry," an 11-foot, 440-pound saltwater crocodile, said Neindorf.
The boy also fed several live animals to Terry by throwing them over the two fences surrounding the crocodile's enclosure, at one point climbing over the outer fence to get closer to the giant reptile.
In the footage, the boy's face remains largely blank, Neindorf said, adding: "It was like he was playing a game."
By the time he was done, 13 animals worth around $5,500 had been killed, including a turtle, bearded dragons and thorny devil lizards, Neindorf said. Although none were considered rare, some are difficult to replace, he said.
"We're horrified that anyone can do this and saddened by the age of the child," Neindorf said.
Alice Springs police said they are unable to press charges against the boy because of his age. Children under age 10 can't be charged with criminal offenses in the Northern Territory. His name was not released because of his age.
Neindorf said he plans to sue the boy's parents.
The boy's small size is probably the reason he didn't trip the zoo's security system, which relies on sensors to detect intruders, Neindorf said.
"I just want people to learn that they can't let their children go and run amok," Neindorf said. "If we can't put the blame onto the child, then someone has to accept the responsibility."