NEW YORK — The Cincinnati police have handed over to a prosecutor the results of their investigation into the actions of the family of a boy whose foray into an enclosure at the city’s zoo led to the killing of an endangered gorilla, officials said Thursday.

The Hamilton County prosecuting attorney said in a statement that the office would review the case and make a determination about whether to file charges as early as Friday.

“No decision has been made at this point,’’ Tiffaney Hardy, a police spokeswoman, said Thursday.

Also Thursday, police released an audio tape of the 911 call placed by the 3-year-old boy’s mother Saturday after he crawled into the Gorilla World exhibit and ended up in the arms of Harambe, a male silverback gorilla weighing around 420 pounds.

The woman’s frantic conversation with an emergency dispatcher brings to light the panic that gripped onlookers as Harambe hovered over the child, at times dragging him by the ankle, for about 10 minutes until zoo workers fatally shot the animal.

“My son fell in the zoo exhibit!’’ the mother, whose name has not been released, says on the call. “My son fell in with the gorilla!’’

“There’s a male gorilla standing over him. I need someone to contact the zoo, please,’’ she says.

“We do already have help started there, OK,’’ the operator tells her.

The mother then calls out to the boy, “Be calm, be calm,’’ she says. “He’s dragging my son. I can’t watch this. I can’t. I can’t.’’

The killing of the 17-year-old ape drew widespread outrage online, directed in part at the zoo over the gap in its fencing as well as its decision to use live rounds instead of a tranquilizer dart.

The boy’s mother, who has declined to be interviewed, has faced the brunt of public anger. By Thursday morning, an online petition calling for her to be investigated for negligence had more than 470,000 signatures.

New York Times