DENVER (KDVR) — If you’re looking to purchase a puppy, make sure you do your homework first.

The FOX31 Problem Solvers have received multiple complaints about a woman allegedly selling puppies up and down the Front Range, out of the back of her vehicle, and in city parks.

Several customers claim their dogs have ended up sick, and at least one couple said their puppy was so ill it died just three days after they purchased it.

Dallas Lussier and MacKenzie Goetz first encountered the woman, who they say calls herself Linda Casey, after stumbling upon a Craigslist post about puppies for sale.

The couple said they were looking to buy a puppy after a tragic miscarriage almost one year ago, and fell in love with a dog on the post.

“To try and fill that void a little bit we decided we were going to get another dog,” Lussier said. “I was like yeah, that’s her. Something just reached out to us.”

Little did they realize their puppy would only lead to more heartache. They say just three days after buying the dog for $300 from Casey in a Target parking lot, the dog passed away.

It turns out Oakley was severely dehydrated and had parvo. The Lussier’s said they spent $3,500 trying to save her.

“For the 12 hours we had her, the little personality we got to see really hit our hearts. I just don’t want anyone else to go through what we had to go through,” Lussier said.

However, sadly others have.

Antonia Duran and her mother purchased two puppies from Linda Casey. The dogs were delivered to her doorstep.

“She just said she rescued the dogs and she wouldn’t really give me any information. He was covered in poop and I was like, that’s not how anyone should receive a dog. That’s not normal,” Duran said.

Aaron Jones with Moms and Mutts, a Colorado rescue for pregnant and nursing dogs said the rescue has received more than two dozen complaints from people who have purchased sick dogs from Linda Casey.

“It’s been happening weekly ever since the end of February. She’s picking up these puppies with no vet care, no background, and bringing them to Colorado and we don’t know what they’ve been exposed to,” said Jones.

The FOX31 Problem Solvers reached out to Linda Casey, who also goes by the name Linda Lantam. She refused to speak with us, but her attorney did.

He said all of the puppies are vaccinated, but not by a veterinarian. Casey does it all herself.

That attorney also said Casey does not have a license to sell puppies in Colorado, because she wasn’t aware she needed one. He said she’s stopped selling dogs until she gets one.

However, many say it’s too late. Nothing can bring back the Lussier’s puppy. Little Oakley is now gone.

“We just want something to happen, whether it’s justice or for her to just stop,” Lussier said.

The Colorado Department of Agriculture says it’s investigating Linda Casey. She was cited by Aurora Animal Services last week for selling puppies in public places after she was confronted by a ranger in Havana Park.

The city of Aurora said she did not have a license.