Preet Bharara, the former U.S. attorney fired by the Justice Department last week, was investigating Health and Human Services Secretary Tom Price at the time of his dismissal, Pro Publica reported Friday.
The former New York attorney's probe concerned the legitimacy of Price’s investments in biotech companies.
Democrats accused Price of using his congressional office to benefit himself, though the former lawmaker insisted that the trades were proper and legal.
The Trump administration last week requested the resignations of 46 U.S. attorneys appointed under former President Obama.
Bharara, who served as the U.S. attorney for the Southern District of New York, refused to resign, prompting the White House to terminate his position.
"I did not resign. Moments ago I was fired. Being the US Attorney in SDNY will forever be the greatest honor of my professional life," Bharara tweeted.
— Max Greenwood contributed.