Last Updated Jun 1, 2016 4:04 PM EDT
CINCINNATI -- A prosecutor's office says police are investigating the circumstances surrounding a young boy entering a gorilla's exhibit at the Cincinnati Zoo and the animal being shot to death to protect the child. The 3-year-old boy (who was initially reported to be 4 years old) is now recovering at home.
The Hamilton County prosecutor's office said Tuesday that police will confer with prosecutors after their investigation is complete.
The endangered gorilla was killed Saturday after the boy got into its enclosure. The boy's family has said he is doing fine.
Cincinnati police said over the weekend that no charges were planned. However, spokeswoman Tiffaney Hardey says police are reviewing the matter and continuing to gather information.
In a statement released Tuesday afternoon, police revealed that their inquiry is focused on the boy's parents:
"Consistent with department policies, the Cincinnati Police Department Personal Crimes Unit is closely reviewing the facts and circumstances that led to [the] boy falling into the Gorilla World enclosure at the Cincinnati Zoo on Saturday, May 28, 2016.... This review is only regarding the actions of the parents/family that led up to the incident and are not related to the operation or safety of the Cincinnati Zoo."
The statement goes on to request that anyone who witnessed the incident or has video of it should contact the police.
Meanwhile, an animal protection watchdog group Tuesday called on federal authorities to hold the Cincinnati Zoo responsible for the death of the gorilla.
The zoo's director, Thane Maynard, said Monday it remains safe for its 1.6 million annual visitors despite the weekend tragedy in which the gorilla was fatally shot to protect a boy who had entered its exhibit. But, he added that a review is underway to determine any improvements that can be made.
Maynard said the powerful gorilla was agitated and disoriented by the commotion during the 10 minutes after the boy fell and that the zoo stands by the decision to shoot 17-year-old Harambe. The boy was taken to a hospital and released Saturday evening; his family said he was "doing just fine" in a statement Sunday. He hasn't been identified publicly.
The Cincinnati-based Stop Animal Exploitation NOW said the U.S. Department of Agriculture, which inspects zoo facilities, should fine the zoo for violating the Animal Welfare Act by having an exhibit in which people can gain access to animals. The zoo didn't immediately respond Tuesday to requests for comment.
Tanya Espinosa, a spokeswoman for the USDA's Animal and Plant Health Inspection Service, said Tuesday there wasn't an investigation open yet, but that the service will "be looking into this incident."
"The (zoo's) barrier obviously isn't sufficient to keep the public out," the watchdog group's executive director, Michael Budkie, told The Associated Press. "Otherwise, Harambe wouldn't be dead."
He said the zoo has had past issues, including in March, when two polar bears wandered through an open den door into a service hallway The zoo reported March 16 that zoo visitors were moved for safety after a male and female bear entered the behind-the-scenes service area, but remained contained.
Zoo staff moved the bears back to their main containment area with two hours, the zoo said at the time, adding that there were no injuries to bears or people.
Jack Hanna, host of "Jack Hanna's Into the Wild," said the zoo made the right call by shooting the gorilla. Hanna said he saw video of the gorilla jerking the boy through the water and knew what would happen if the animal wasn't killed.
"I'll bet my life on this, that child would not be here today," Hanna told CBS affiliate WBNS-TV.
A Cincinnati police spokesman said Sunday that no charges against the parents were being considered.
More than 300,000 people have signed a petition calling for the boy's parents to be held accountable, CBS News' Jamie Yuccas reports.
Wildlife biologist Jeff Corwin isn't placing blame but says the public should be more attentive, saying "the zoo isn't a baby sitter."
A spokeswoman for the family said Monday they had no plans to comment.
"I do think there's a degree of responsibility they have to be held to," said Kate Villanueva, a mother of two children from Erlanger, Kentucky, who started the "Justice for Harambe" page and attended a Monday vigil for the gorilla outside the Cincinnati Zoo.
The Gladys Porter Zoo in Brownsville, Texas, where Harambe spent most of his life, said its staff is deeply saddened by the gorilla's death. Harambe was sent to Cincinnati less than two years ago in hopes he would eventually breed with gorillas there.
Jerry Stones, facilities director at Gladys Porter Zoo raised Harambe since birth and has worked with the gorilla's family since they first entered the U.S., the Brownsville Herald reported. He spoke Monday about his relationship with Harambe.
"He was a character. He grew up to be a beautiful, beautiful animal, never aggressive and never mean," Stones said, according to the newspaper. "He would tease the heck out of people and would do things to irritate you just like some kids."
Stones said he would take Harambe home with him when the gorilla was a baby and let him sleep on his bed, according to KRGV-TV.
There are critics of the zoo's decision to kill Harambe. The People for the Ethical Treatment of Animals said the zoo should have had better barriers between humans and the gorillas.
Maynard said the atmosphere following the incident is "very emotional."
"Not everyone shares the same opinion and that's OK," he said. "But we all share the love for animals."
Maynard said the zoo has received messages of support and condolences from around the world, including from other zoo directors and gorilla experts. He said zoo visitors have been leaving flowers at the exhibit and asking how they could support gorilla conservation.