Tucked into a rural section of Louisiana, a few miles from Lafayette, an unexpected compound springs from the landscape. It is the nation's largest primate testing lab. The New Iberia Research Center, part of the University of Louisiana, houses more than 6,000 primates and one of the largest captive populations of chimpanzees in the world.
"Nightline" obtained the results of a nine-month undercover investigation by the Humane Society of the United States. A Humane Society investigator took a hidden camera inside the New Iberia Research Center for most of 2008. The video shows what the Society says is the way monkeys and great apes are treated behind closed doors.
The New Iberia Research Center is a public facility, and its research includes contract work for pharmaceutical companies and hepatitis studies. The lab receives millions in public funding but limited public scrutiny.
"Facilities are very secretive in general," said the investigator, who asked to remain anonymous because of the investigation. "It's hard to get a lot of good information out of what really goes on. You rarely see images other than what is kind of posted on the Web sites. Going undercover in a place is the only way you'll see what's the truth."
The Humane Society investigator told ABC News that chimpanzees, often perched several feet off the ground, are shot with sedation guns, with little regard for their safety. The video shows chimps crashing to the floor.
"The sedated chimp would be sort of rocking slowly on the perch, then, out of nowhere, they just smack to the floor," the investigator said. "It was horrific to watch and to hear."
The Humane Society investigator who gained access as an employee shot video of a lab worker striking a restrained monkey's teeth three times with a pipe. The investigator says the employee wanted the monkey to open its mouth.
"The man is sort of threatening him [the monkey] with this pole and smacking his teeth at the same time," the investigator said, describing the video.
Another piece of video shows a lab employee hitting an infant monkey in the head and swearing when the monkey bites at her finger.
In response to "Nightline's" repeated requests for an interview, the University of Louisiana, which houses the New Iberia Research Center, issued a statement to ABC News, which said in part:
"The university takes very seriously the New Iberia Research Center's responsibility to care for the animals housed at the center. The highly qualified and experienced staff veterinarians responsible for the care of these animals are extremely dedicated and respond aggressively to reports of potential animal abuse," wrote Dr. Joseph Savoie, president of the University of Louisiana at Lafayette. "We have a clearly stated and direct no tolerance policy when the welfare of any animal in our care is threatened, and we will continue to strictly enforce that policy."
The Federal Animal Welfare Act, the law designed to protect these primates, requires labs to ensure that procedures avoid or minimize distress or pain. The law also requires that animals be handled with proper care.