(CNN) -- The U.S. Department of Agriculture said Monday that it's investigating "personnel issues" at a California slaughterhouse after an exclusive CNN investigation detailed how officials believe Rancho Feeding Corporation triggered one of the biggest meat recalls in years.
Federal investigators believe that Rancho processed cancerous cows when government inspectors weren't there, triggering a massive recall of nearly 9 million pounds of meat and a criminal investigation, according to sources familiar with the probe.
And in the plant where it all went down, a government inspector and a Rancho foreman were involved in an inappropriate romance, according to documents obtained by CNN.
A USDA spokesman told CNN the department "is conducting a thorough investigation into personnel issues related to this case. We are not permitted to discuss the details of the case at this time as doing so could jeopardize the ongoing investigation."
Federal officials familiar with the investigation said that the U.S. attorney's office in San Francisco, which is conducting the criminal investigation, is looking into the relationship between the inspector and foreman, but so far officials haven't connected it to the recall. The U.S. attorney's office did not respond to a request for comment.
While brief, the USDA statement is somewhat substantive, a departure from the department's practice of referring questions to the U.S. attorney's office without comment.
Democratic Rep. Rosa DeLauro of Connecticut also weighed in, calling CNN's report, "deeply troubling."
"Rancho and USDA are going to have to explain themselves to American consumers," DeLauro, a member of the House subcommittee on agriculture, said in a statement. "I am deeply concerned that the Food Safety Inspection Service failed to prevent this deception from happening."
DeLauro's not alone. Democratic Rep. Jared Huffman, whose district included the now-defunct Rancho plant in California, wants answers. Instead, he's gotten only "crickets" from the U.S. attorney's office.
"This is radio silence from the federal agency that did something very significant in my district that is affecting lots and lots of people," he said. "I've never seen anything quite like it."
Investigators believe that Rancho was buying diseased dairy cows and processing them when government inspectors weren't there. After the cows were killed, employees would hide the warning signs of cancer by trimming off diseased parts, using a fake stamp of approval or even replacing the heads of sick cows with ones from healthy animals. It's unclear which employees were involved, officials said.
A federal law enforcement source told CNN that charges against Rancho's former owners -- the plant has since been sold -- have been decided. But that decision has yet to become public.