IOWA CITY — The trucking company linked to the recent deadly human smuggling case in Texas had promoted itself as an American success: a family firm whose hard-working drivers helped keep the U.S. economy running.

But behind that image was a cutthroat business that flouted federal laws for years, yet managed to stay afloat despite financial troubles and tangles with prosecutors, regulators and tax collectors, according to public records and interviews with former drivers.

Now, Pyle Transportation faces the biggest threat to its survival yet after one of its contract drivers was charged Monday in the deaths of 10 immigrants found in a sweltering Pyle trailer in San Antonio's 100-degree heat. Investigators are scrutinizing Pyle's claim that it knew nothing about an operation that federal authorities have described as sophisticated and possibly linked to a Mexican cartel. Federal regulators have launched an investigation into the company's safety record.

The driver, 60-year-old James "Bear" Bradley Jr., told investigators he was unaware any immigrants were in the trailer, saying he heard their pleas after stopping Sunday at a Walmart to urinate. Investigators said dozens of immigrants were packed into the dark trailer after being smuggled across the border.

Company owner Brian Pyle denied any knowledge of human smuggling, but declined to comment Monday on the company's operations and did not return additional messages left Thursday seeking comment. On its website, which has since been taken down, Pyle Transportation advertised its fleet of high-end rigs and boasted of delivering refrigerated shipments of meat and produce on time to customers from its rural Iowa base. Playing upbeat music and flashing photos of smiling truckers, the site touted love of country, faith in God and the company's slogan: "Keepin' it Cool Since 1950."

Yet former drivers told the Associated Press the company routinely pushed them to violate federal safety rules. They say they were pressured to drive too many hours without rest, to falsify their logs to conceal those violations and to transport overweight loads on unrealistic deadlines. They said they faced retaliation if they complained and that Pyle refused to pay wages they were owed when they quit.

Two of Bradley's former Pyle colleagues were stunned to learn about the deaths and struggling to understand what happened.

"Knowing Bear, the pieces don't fit," said Paul Terry, 68, of Denver. "I believe Bear was set up. He is a country boy and he don't know that much. No way in the world could he orchestrate something like that. I will say that on my kids' grave."

Former driver Tim Moffitt said Thursday he believed the company had to have some knowledge of the operation, calling it a good place to work only "if you don't like rules."

"They are always looking for ways to save money and make money," said Moffitt, who has known Bradley for 30 years.

Brian Pyle told the AP Monday the company sold the trailer and hired Bradley as a contractor to drive it to the border city of Brownsville, Texas, to deliver it to the buyer, whom he refused to identify. He showed a reporter what he said was a bill of sale dated May 10 that had no price.

Bradley told investigators he was unaware of the trailer's contents, adding he knew its refrigeration system didn't work, according to the complaint against him. He described taking a looping route with stops in Laredo and San Antonio, several hours west of Brownsville.

Pyle said Bradley was given an address and told to deliver the trailer last Friday, disputing Bradley's claim to investigators he had been given neither a location nor a time to make the delivery.

The company's relationship with Bradley was reflected on its now-defunct website, where he was pictured smiling with Pyle in its "Hall of Fame" of workers.

Pyle Transportation has long been an influential company in Schaller, a northwest Iowa town of 750 that doesn't have a police officer. Residents said it was run by the late Don Pyle before facing troubles in the 1990s after it was passed to his son, Michael.

The son and his Pyle Truck Lines pleaded guilty in 2001 to falsifying Department of Transportation records and were put on probation. Michael Pyle's children took control of the business a few years later when Pyle Transportation formed, but he remained involved. Michael Pyle declined comment, hanging up on a reporter who called Thursday.

The IRS alleged in 2015 Pyle Transportation refused to pay employment and highway use taxes for years, racking up $150,000 in liabilities.

The company also has been ordered to pay penalties for falsifying records on drivers' hours and has been operating with a "conditional" safety rating, meaning it had been out of compliance with regulations.

Bradley went to work for the company in 2010 in response to an internet ad, and later recruited Terry and Moffitt to join him, they recalled. Terry said at first they made good money delivering pork from Iowa slaughterhouses to Texas and returning with loads of produce and steel. But Terry and Moffitt left after employment disputes.

"They will run you to death and you have to falsify your logs to make it work," said Terry, who according to court records has been unable to collect a $2,000 judgment for unpaid wages he obtained after quitting in 2014.

Cody Winters, 29, of Charles City, Iowa, said he would be stunned if Pyle was complicit in smuggling even if the company was "crooked' in other ways. He sued the company to collect $3,300 in unpaid wages after he was fired and left stranded at a truck stop in 2015.

"They appeal to drivers by keeping big Peterbilts to drive. But then you get there and it's not good at all. It's just a show," he said. "I thought, 'How is this place even staying in business?'"