As the chorus of criticism grows over the killing of a gorilla to save a boy at a Cincinnati zoo, police plan to investigate the child’s family.

Zoo officials shot dead Harambe to save a 3-year-old who slipped into the animal’s enclosure Saturday.

The gorilla dragged the boy across a moat and after a 10-minute encounter, Cincinnati Zoo officials fatally shot the beloved and endangered gorilla. The boy was not seriously injured.

The zoo has performed a necropsy on the gorilla, but has not released any details on the results.

A research doctor extracted and froze the gorilla’s genetic material after his death, the zoo said.

Review aimed at parents

Cincinnati police said Tuesday that their review will focus on the actions of the boy’s parents and family. It is not related to the operation or safety of the Cincinnati Zoo, authorities said.

“After the review, we will determine if charges need to be brought forward,” police spokeswoman Tiffaney Hardy said.

“If it is determined charges need to be brought forward, we would then discuss it with the Hamilton County prosecutor’s office.” The prosecutor’s office declined to say how long the investigation might take.

Authorities have said the boy’s mother was with the child when he slipped past a fence and tumbled into the moat.

Critics united in grief

Harambe’s name is Swahili for come together in unity for a common cause. And critics have rallied together against the gorilla’s killing.

Uproar and vitriol has poured in especially on social media against the boy’s mother after zoo officials said they opted to kill the western lowland silverback to protect the boy.

Some suggested the boy’s parents should be held criminally responsible for the incident. An online petition seeking “Justice for Harambe” earned more than 100,000 signatures in less than 48 hours.

“This beautiful gorilla lost his life because the boy’s parents did not keep a closer watch on the child,” the petition states.

Kimberly Ann Perkins O’Connor, who saw the incident, said the boy told his mother he was going to get into the moat. The mother admonished him to behave before she was distracted by other children with her, O’Connor said.

“The little boy himself had already been talking about wanting to go in, go in, get in the water and his mother is like, ‘No you’re not, no you’re not,’ ” O’Connor said. “Her attention was drawn away for seconds, maybe a minute, and then he was up and in before you knew it.”

‘The child is safe’

Thane Maynard, the zoo’s director, has forcefully stood by the decision to kill the gorilla.

“We are all devastated that this tragic accident resulted in the death of a critically endangered gorilla,” Maynard said at a news conference.

However, he said, those second-guessing the call don’t understand the 450-pound animal.

“That child’s life was in danger. People who question that don’t understand you can’t take a risk with a silverback gorilla — this is a dangerous animal,” he said. “Looking back, we’d make the same decision. The child is safe.”

Famed primatologist Jane Goodall’s response to the killing highlighted the conflicted nature of the decision to kill the animal.

“I feel so sorry for you, having to try to defend something which you may well disapprove of,” Goodall wrote in an email to Maynard.

Goodall described the killing as “a devastating loss to the zoo, and to the gorillas.”

More investigations

The Association of Zoos and Aquariums announced it’s investigating the incident.

“We’ll of course be … working with Cincinnati to figure out what happened and make sure we can firm that up so it doesn’t happen again,” said to Rob Vernon, a spokesman for the agency, which accredits zoos.

The U.S. Department of Agriculture, which inspects the zoo annually, said it will determine whether the facility was in compliance with the Animal Welfare Act.

If not, that would warrant a formal investigation, said Tanya Espinosa of the USDA.

CNN independently reviewed USDA records for the past three years, which is all that is maintained by the agency. It found nine findings where the zoo was out of compliance. None involved the gorilla exhibit.

Two involving veterinary care were directly tied to the health or wellness of the animals, and seven dealt with other issues.

All were resolved, according to USDA reports.

Zoos, circuses, and marine mammal parks are regulated under the Animal Welfare Act, a federal law that monitors the treatment of animals in research and exhibition. The act is enforced by the U.S. Department of Agriculture.

Animal rights group steps in

An animal rights group has requested an investigation by the USDA.

Stop Animal Exploitation Now alleges the zoo violated the Animal Welfare Act,according to a letter by Michael A. Budkie, its executive director.

The letter cites inspection reports from the USDA database dating to March this year and November 2014.

The March report documented an incident in which two polar bears got into a service hallway accessible only to zookeepers. The dangerous animal response team quickly secured the area and used tranquillizer darts to subdue the bears.

Thane Maynard, the director of the Cincinnati Zoo, noted a zookeeper lost her arm in the incident.

The November 6, 2014, report cites a door to an outdoor monkey enclosure had multiple wooden boards in disrepair. It also detailed deterioration in a horse enclosure.