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Cosima Allen, 11, says she and her family are heartbroken after losing their new puppy, Scottie, who they got off of Craigslist.

The Allen family saw an ad for a healthy white Maltese Yorkie mix that had all its shots, and so they bought the pup for around $600. But after taking him to the vet and paying a $1,200 bill, the family learned Scottie was ill and tested positive for Parvo.

Just five days after arriving at their San Fernando Valley home, Scottie passed away, the family says.

The Allens say when they contacted the woman who sold them the dog, who they identified as Kaley Cortini, she denied the transaction ever took place. They’re now suing her.

Several others say they were also sold sick puppies from the same woman on Craigslist. Although it’s against the website’s policy to sell pets on the site, people are allowed to post pets up for adoption and some backyard breeders are placing ads charging a “rehoming fee.”

“To anybody, just don’t buy a dog from Craigslist,” Allen said. “We heard about scammers but never really thought it would happen to us.”

“People trying to buy cheap because they don’t have money to get one of those cute puppies their kids dream about,” her mom, Claudia Allen, said.

In California it’s illegal to sell puppies in a public place. Animal advocates say the best way to adopt a dog is through a local rescue or shelter. The Animal Legal Defense Fund is trying to stop the selling of pets online.

KTLA reached out to Cortini for an interview but had not received a response Tuesday night.