(CNN) -- A Connecticut woman pleaded for police to "please hurry" to save a friend from an attack by a pet chimpanzee, according to emotional 911 recordings released Tuesday by Stamford police.

Police say Travis, seen here as a younger chimp, was like a child to his owner, Sandra Herold.

"He's ripping her apart," Sandra Herold, 70, tells dispatchers about her pet, Travis.

With the chimp squealing in the background, Herold cries out, "He's killed my friend!"

The victim, Charla Nash, 55, remains hospitalized with life-threatening injuries after the chimp, once featured in television commercials for Coca-Cola and Old Navy, attacked her Monday afternoon, police said.

Nash had just arrived at Herold's house when Travis jumped on her and began biting and mauling her, causing serious injuries to her face, neck and hands, according to Stamford Police Capt. Rich Conklin. Conklin said the attack was unprovoked, but he described it as "brutal and lengthy." Watch how owner made frantic call to police »

Herold had called Nash to her house to help get 14-year-old Travis back inside after he used a key to escape.

While her friend was being attacked, Herold was unable to pull the primate off. She then called 911 before stabbing the chimp with a butcher knife and hitting him with a shovel. Neither fazed Travis, who police said had been like a child to Herold.

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A Stamford police officer later shot the chimp multiple times after the primate went after him inside a police cruiser, Conklin said. Travis returned to the house, where police found him dead. Conklin estimated that Travis weighed close to 200 pounds.

Conklin couldn't confirm media reports that the chimp had Lyme disease, though he did say investigators were taking their time with the case to determine what may have provoked Travis to attack Nash. Animals often do not exhibit symptoms of Lyme disease, caused by the bite of certain types of ticks, although aggression is a possible symptom, according to the Centers for Disease Control and Prevention.

Conklin said Nash had recently gotten a haircut that changed her appearance significantly. Conklin said the chimp had been acting "rambunctious" earlier, prompting Herold to put Xanax in a cup of tea for him to drink. He did not know if the animal had been prescribed the medicine or if Herold had ever given her pet such a mixture before. Watch wildlife biologist Jeff Corwin talk about the dangers of chimps »

Conklin added that his department is not used to dealing with cases such as this, and they were trying to familiarize themselves with laws and regulations before deciding if charges will be filed.

Conklin said this isn't the first interaction his officers have had with Travis. The chimp, who was well known and liked in the community, escaped in 2003 and "wreaked havoc" on the streets of Stamford for a couple of hours, Conklin said.

Travis' body was removed from the home and taken to two locations: His head was taken to the state lab for a rabies test and the body was taken to the University of Connecticut for an animal autopsy. Conklin said this is standard procedure.

The chimp, who was known to walk around town, sometimes without a leash, also liked to surf on the Internet and was able to change the TV channel with a remote, according to a Stamford Advocate article. The paper also reported that Travis watered plants, was able to feed hay to his owner's horses, ate at a table with the rest of the family and sometimes drank wine from a stemmed glass.

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