Jeffrey Knox, the former head of the Justice Department’s criminal fraud section, has joined Simpson Thacher & Bartlett as a Washington-based partner in the law firm’s government and internal investigations group, the firm announced Tuesday.

Knox’s last day as a federal prosecutor was Friday. He was previously an associate at Simpson Thacher prior to joining the government.

Knox is the latest high-ranking Justice Department official in recent months to join a corporate law firm, where former federal prosecutors are coveted hires who can offer clients insight into how to navigate federal agencies. At least three from the agency’s criminal division have joined Covington & Burling since 2013, and Charles Duross, one of the department’s key enforcers of federal foreign bribery laws, joined Morrison & Foerster in January.

As head of the fraud section of the criminal division, Knox oversaw the prosecution of securities, healthcare and financial fraud, and the enforcement of the Foreign Corrupt Practices Act, which forbids U.S companies from bribing foreign officials to further their business interests abroad. During his tenure, the Justice Department investigated global financial institutions for violations relating to the alleged ma­nipu­la­tion of LIBOR, an interest rate standard many lenders use to establish their own rates.

Prior to joining the department, Knox was an assistant U.S. attorney in the Eastern District of New York, where he served as chief of the violent crimes and terrorism section and prosecuted post-9/11 terrorism cases.

Knox “is greatly respected within both the [Justice Department] and the white collar bar,” Mark Stein, head of Simpson Thacher’s government and internal investigations group, said in a statement. “His experience and insight will provide substantial value to our clients.”

Simpson Thacher is headquartered in New York and has about 850 attorneys in 10 offices around the world.