STAMFORD, Conn. -- The owner of a chimpanzee that violently mauled a family friend at a Stamford home Monday claims the animal was suffering from Lyme disease.

Police said they are working to get the 200-pound chimp's medical records to corroborate the story. Officials said they are investigating what medication the animal was taking and how long he may have had the disease.

Woman Brutally Attacked By Chimp

The pet chimpanzee, named Travis, attacked 55-year-old Charla Nash at its Rockrimmon Road home Monday afternoon after it got out of the house.

“The animal is so intelligent, he grabbed the keys, unlocked the kitchen door to allow itself out," Stamford Police Capt. Richard Conklin said.

Nash was coming with an orange toy to help Travis' 70-year-old owner, Sandra Herold, calm the animal, who police said had been agitated all day.

Herold gave the chimp tea laced with Xanax in an attempt to calm him. When that didn't work, police said Herold called for Nash's help.

Police said Travis violently attacked Nash as she exited her vehicle. They called the attack "lengthy and vicious."

Herold called 911 and went to help her friend. Police said she stabbed Travis, whom they said she raised like a child, several times with a kitchen knife before police arrived. Police said Herold also tried hitting Travis with a shovel in an attempt to get him to stop attacking Nash.

“She ran to the kitchen, grabbed a butcher knife and stabbed her chimp," Conklin said.

Police said Travis can be heard screaming during Herold's 911 call.

Police said Travis then ran over to police cruisers and broke a mirror off one of the vehicles before opening a cruiser door. Stamford police said the chimp moved as though he was going to attack the officer, prompting the officer to shoot the animal in the chest at close range.

Travis then ran off, and police said officers following the blood trail found him dead in his living quarters inside the home.

Nash was transported to Stamford Hospital with life-threatening and "life-changing injuries," police said. Neighbors told Eyewitness News that the chimp bit the woman's hands off.

"He bit both of her hands off," said Herold's friend, Lynn Mecca. "The cop said he was eating … it’s terrible. I don’t want to talk about it."

“I would have never thought Travis was capable of doing this. I don't think anybody was," said Michael Grant, who’s known Herold for years. “Last time I saw Travis, he was in one of the upstairs windows giving monkey cries in the neighborhood. You'd think you were in Africa."

Police said Herold was also taken to the hospital with unknown injuries. The officer whom the chimp lunged at was transported to the hospital for shock and trauma treatment, police said. The officer has since been treated and released.

Doctor: Psychosis, Rage Common With Lyme Disease

Dr. Charles Ray Jones, a Lyme disease specialist in New Haven, sees patients from across the country.

Jones said common behaviors of the disease are psychosis and rage.

"Sometimes they have to be on psychotropic medication to control it, then they have to come off," he said. ""We've had several children who've had such bizarre and violent reactions that they've had to be hospitalized in a psychiatric unit."

Jones said he has also seen family pets with the disease act out.

"They are very strong, very powerful animals. Just because it is raised by humans does not make it domesticated. It is still a wild animal and wild animals can have unpredictable episodes of aggressive behavior." -- Dr. Colleen McCann Primatologist, Wildlife Conservation Society's Bronx Zoo

"I have had kids here who have had pet dogs and cats with behavioral changes from Lyme disease," Jones said. "It's usually not just irritability, but rages and depression."

Dr. Colleen McCann, a primatologist with the Wildlife Conservation Society's Bronx Zoo said the most serious issue that would explain the chimp's behaviors is that its owner treated it as a pet.

"Aside from the issue of Lyme disease, chimps can cause grave danger to humans when kept in private ownership," she said. "They are very strong, very powerful animals. Just because it is raised by humans does not make it domesticated. It is still a wild animal and wild animals can have unpredictable episodes of aggressive behavior."

Police said experts may study the chimp's brain tissue to help determine what caused its aggressive behavior.

Travis Starred In National Ads

Neighbors told Eyewitness News that Travis was like a part of Herold's family and that she viewed him as her own child. "She lived for this chimp," said Mecca. "This chimp was like her child."

Neighbor Tony Marcari said he used to play around with Travis and wrestle with him. He said the animal always knew when to stop and paid close attention to his owner.

"He listened better than my nephews," Marcari said. "I just don't know why he would do that."

Other neighbors said Travis was well-known around town and that he used to play with police officers, pose for photos and even appeared in several commercials, including ads for Coca Cola and Old Navy.

Monday was not the animal's first encounter with the law. The chimp escaped from a vehicle in downtown Stamford in 2003 for several hours before police put down the animal with a tranquilizer gun. Police described that incident as somewhat playful and mischievous.

Officers used cookies, macadamia treats and ice cream in an attempt to lure him, but subdued him only after he became too tired to resist.

At the time of the 2003 incident, police said the Herolds told them the chimpanzee was toilet trained, dressed himself, took his own bath, ate at the table and drank wine from a stemmed glass. He also brushed his teeth using a Water Pik, logged onto the computer to look at pictures, and watched television using the remote control, police said.

Lawmakers Call For Renewed Chimp Act

The chimpanzee attack has sparked lawmakers and the Humane Society of the United States to renew calls for passing the Captive Primate Safety Act.

U.S. Reps. Earl Blumenauer, D-Oregon, and Mark Kirk, R-Illinois, along with the Humane Society, lead the call for the legislation, which would prohibit interstate commerce in primates for the pet trade, making it illegal for individuals to buy or transport a pet primate across state lines. It would have no impact on zoos or research.

"Given the patchwork of state and local laws and the interstate nature of the primate pet trade, a federal response is urgently needed," said Michael Markarian, executive vice president of the Humane Society. "Primates are wild animals who can attack and spread disease, and they don't belong in our bedrooms and basements. It's time to end this dangerous monkey business."

Connecticut allows primates as pets with a state permit. The rule grandfathered animals who were already in the state on Oct. 1, 2003, but only for smaller species that weigh up to 50 pounds at maturity. The permit requirement applies to all chimpanzees. Twenty states and the District of Columbia prohibit keeping primates as pets. Click Here To Read Full Story.