By Lauren DiSpirito

WESTMINSTER, Colo. (CBS4)– Investigators are trying to find a man accused of illegally selling puppies that are too young to be separated from their mothers. Police believe he is operating in Colorado and surrounding states, and may be part of a larger puppy mill ring.

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Kayla Brown, of Aurora, encountered the man when she says she used Craigslist as part of her search for a companion to her 11-year-old pug, Mark. Her parents had had success finding a healthy dog through the website, Brown says.

Kayla Brown (credit: CBS)

Kayla Brown (credit: CBS)

This summer, she met a man who went by “Jason” in Westminster, where he promised to deliver a healthy, 8-week-old female pug. He’d sent her pictures of a healthy pug, but at their meeting, Brown says the man showed up with a male pug that did appear to be well-cared for.

“He brings out this pug puppy that barely fit in my hand and I knew something was wrong,” Brown said. “It wasn’t acting normal and I couldn’t leave him there, I just couldn’t.”

(credit: CBS)

(credit: CBS)

When the man tells Brown he cannot provide shot records for the pug, she says she used that as leverage to negotiate down the man’s asking price, paid him $420 in cash, and took the puppy home with her. She says the pug could barely eat, and the next day, a veterinarian confirmed her suspicions. The pug was just five weeks old, she was told, and so sick, he required extensive medical care. After calling a Colorado pug rescue group, Brown agreed to give the dog to a foster family more prepared to care for the young puppy.

Determined not to let the man get away with his actions, she enlisted the help of a friend, who Brown says contacted the seller, telling him she was interested one of his pug puppies. Days later, they met in Westminster.

(credit: CBS)

(credit: CBS)

“I know I’ll never see that money again,” Brown said. “It’s that these animals need to be rescued.”

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Her friend recorded video of the interaction, which Brown shared with CBS4 and investigators. In the video, the man can be heard telling the prospective buyer the puppy is eight weeks old.

(credit: CBS)

(credit: CBS)

“That’s a little small for eight weeks to me,” the woman recording the video says.

He replies, “There were eight in the litter, that’s why they’re smaller than normal.”

Westminster Police spokeswoman Cheri Spottke confirms the department is investigating the man and believes he may still be selling puppies to unsuspecting people around Colorado. Spottke says state Department of Agriculture officials have joined the investigating and are looking into the possibility the man is tied to an out-of-state puppy mill. Some puppies he’s accused of selling illegally were covered in ticks, which transmit Lymes Disease to humans, Spottke said.

(credit: Facebook)

(credit: Facebook)

In Colorado, it is illegal to sell puppies that are fewer than eight weeks old.

Spottke warns against buying dogs through Craigslist, saying sometimes what looks like a “deal” can end up costing owners thousands of dollars in vet bills.

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(credit: CBS)

(credit: CBS)

Lauren DiSpirito reports for CBS4 News at 10 p.m. She covers breaking news and feature stories along Colorado’s Front Range. Follow her on Twitter @CBS4Lauren. Share your story ideas with her here.