(PITTSBURGH) -- The Pittsburgh Zoo & PPG Aquarium said the mother of a 2-year-old boy is at fault in the death of her son, who was mauled to death by a pack of African painted dogs last year.
The zoo's attorney wrote in a filing that Elizabeth Derkosh failed "to maintain a proper grasp" after she lifted her son, Maddox Derkosh, onto a railing on Nov. 4, 2012, so the boy could get a closer look at the animals. The boy squirmed loose from his mother's grasp, but then lost his balance and fell into the enclosure, where he was immediately attacked by the animals, according to witness reports released by police.
The filing was in response to a wrongful death suit filed by the Derkosh family, which lives in Pleasant Hills, Pa.
Robert Mongeluzzi, an attorney for the Derkosh family, told ABC News that zoo's response was "dead wrong and shameful."
"The zoo, in its court filing, attacked Maddox's grieving mother although the zoo had been warned by several of its own employees of the very tragedy that would take Maddox's life, ignored the warnings, and told at least one of those employees that 'this is not your concern, go back to work,'" he said.
Tracy Gray, a spokeswoman for the zoo, declined further comment due to the pending litigation.
After Maddox Derkosh fell, zookeepers ran into the enclosure, luring seven of the dogs away. Other zoo officials tried to beat back the remaining dogs. The most aggressive dog was shot and killed by a Pittsburgh police officer.
African painted dogs are an endangered species and are about the size of a medium-sized domestic dog, according to the zoo. African wild dogs are also known as cape hunting dogs, spotted dogs and painted wolves. They have large, rounded ears and dark brown circles around their eyes.
Since Maddox's death, the exhibit has been closed and the dogs have been sent to zoos across the country.
Copyright 2013 ABC News Radio