The original whistleblower complaint from Gary Shapley, a 14-year veteran of the agency, was revealed in an April 19 letter to members of Congress. Since then, Shapley and his attorney, Mark D. Lytle, have alleged retaliation.

In an interview with CBS News that aired Wednesday night, Shapley identified himself as an IRS supervisory agent, who says he was assigned to an investigation in January 2020 - the subject of which he said he couldn't legally identify due to tax secrecy laws, but which CBS said was the Hunter Biden case. Shapley and his legal team are simply calling it an "ongoing and sensitive investigation of a high-profile, controversial subject."

Lytle says his client's disclosures contradict sworn testimony by a "senior political appointee," and involve "failure to mitigate clear conflicts of interest."

He added that the whistleblower disclosures show "examples of preferential treatment and politics improperly infecting decisions and protocols that would normally be followed by career law enforcement professionals in similar circumstances if the subject were not politically connected."

According to Shapley, "When I took control of this particular investigation, I immediately saw deviations from the normal process. It was way outside the norm of what I've experienced in the past."

In March, U.S. Attorney General Merrick Garland told the Senate Judiciary Committee that the U.S. Attorney in Delaware had full discretion in pursuing the Hunter Biden tax investigation and was "not restricted in his investigation in any way." Shapley, however, has claimed that, in his investigation, "there were multiple steps that were slow-walked—were just completely not done—at the direction of the Department of Justice."