By Suzannah Gonzales
(Reuters) - Prosecutors are reviewing a police investigation into the parents of a 3-year-old boy who fell into a gorilla enclosure at the Cincinnati Zoo on Saturday, prompting the killing of an endangered gorilla.
A statement on the website for Hamilton County Prosecutor Joseph Deters said the earliest he would conclude his review would be Friday.
Cincinnati police have said the child's parents and family were the target of the probe and not the operation or safety of the zoo.
The Cincinnati Zoo said on Thursday it has reevaluated its Gorilla World exhibit and will modify the railing that surrounds it. It plans to complete the modifications by Tuesday, when the exhibit is scheduled to reopen.
The 17-year-old western lowland silverback gorilla, named Harambe, was shot and killed by Cincinnati Zoo staff after the boy fell into his enclosure within Gorilla World. Western lowland gorillas are critically endangered and the killing of Harambe triggered intense criticism of the zoo and the boy's parents.
Witnesses said the boy had expressed a desire to get into the enclosure and climbed over a 3-foot (1-meter) barrier, then fell 15 feet (4.6 m) into a moat.
The new barrier is 42 inches (107 cm) high with wood beams at the top and bottom and knotted rope netting, the zoo said in a statement. It did not say how high the previous railing was but said it had passed multiple inspections by the Association of Zoos and Aquariums.
"Our exhibit goes above and beyond standard safety requirements, but in light of what happened, we have modified the outer public barrier to make entry even more difficult,” said Thane Maynard, director of the Cincinnati Zoo in a statement.
The family, whose name has been withheld by police, has declined to comment on the investigation. They said on social media that the child had a concussion and some scrapes, and through a spokeswoman on Wednesday that he was doing well.
Outrage over the gorilla's death has mounted, and online petitions at change.org have collected hundreds of thousands of signatures demanding "Justice for Harambe."
The animal rights group Stop Animal Exploitation Now said on Tuesday that it would file a negligence complaint against the zoo with the U.S. Department of Agriculture. The group is seeking the maximum penalty of $10,000.
U.S. zoos are left to decide under federal rules how to make animal exhibits safe.
(Reporting by Suzannah Gonzales in Chicago; Additional reporting by Laila Kearney in New York; Editing by Cynthia Osterman)