A bogus pet-shipping website that tricks people into thinking they're dealing with Delta Air Lines is also linked to a scam that preys on people hoping to buy dogs such as Chihuahuas, poodles and corgis, the airline says in a court filing.

Delta, one of the world's largest airlines says its wide-ranging investigation into the pet shipping website uncovered a "larger criminal scheme."

Delta filed a federal lawsuit last month over a website that it says tricks people into thinking they're dealing with the airline when arranging for their pets to fly on jets.

The airline says the site — DeltaPetTransit.com — is designed to look like a Delta site and uses the airline's logos and pictures of its planes.

In court records filed this week, the airline says its investigation has turned up numerous sites using the Delta name that promise to ship pets or advertise dogs for sale.

The website operators collect thousands of dollars without shipping or delivering any pets, Delta maintains.

Even after people pay the purchase price for a "non-existent dog," the website operators "demand still more payments for 'mandatory' insurance, vaccines, permits, and other 'required fees," Delta wrote in court filings.

"In truth, however, defendants have no dogs for sale, provide no shipping services, and instead retain as the proceeds of their theft-by-deception all payments made by their various victims," Delta's lawyers wrote.

The airline's investigation involves several subpoenas of Google and other internet companies as it tries to identify the operators behind the sites, so it can name them as defendants in its lawsuit.

As part of that effort, Delta is seeking to obtain grocery store surveillance video of an unidentified man who picked up a pet-related payment inside a grocery store in Colorado Springs, Colorado.

Delta's investigator had gone on one of the websites and sent a wire payment via Western Union. The man picked up the payment Oct. 18 at a Western Union office inside a King Soopers grocery store. Delta asked a judge this week for authorization to subpoena the video from the grocery store's parent firm, Kroger Co.

Delta on Friday had no immediate comment on the ongoing case Friday.

The airline has identified several other websites which it says are using its name without permission, including DeltaPetAirways.com , court records show. That site uses the Delta name, but also references Delta rival American Airlines and its AAdvantage frequent flyer program.

Delta says it has evidence linking the pet transport sites with the phony dog-selling sites, and the airline believes it's all part of the same scheme.

One of the websites cited in court records advertises "Mini Goldendoodle Puppies." The site includes a lengthy description of how the puppies are lovingly raised. A shipping section of the site includes prices and details of how the dogs are supposedly transported to their new home via airlines.

"At about five weeks of age we start taking them out on car trips, this not only accustoms them to travelling but also to being confined to a crate for short periods of time," the website states. "Weather permitting they go outside for play sessions and are soon happy to toilet on grass, block paving, stones and concrete as well as newspaper. By the time they are ready to leave mum they are pretty bomb-proof and well prepared for life in the big wide world."