Post-9/11, Sherwin joined the intelligence staff of General Tommy Franks at the United States Central Command assisting in the planning of military combat operations in Afghanistan and Iraq.

[10] In 2018 Sherwin joined the Miami office's national security section where he prosecuted counterintelligence cases, economic espionage, and state-sanctioned theft of trade secrets and digital currency.

[4][12] In September 2019, Sherwin won the conviction of a Chinese woman, Yujing Zhang, who trespassed at President Donald Trump’s Mar-a-Lago Club in Florida.

[15] Sherwin approved the decision to give to Flynn's defense team internal FBI records that the government cited in its dismissal motion, an official told The Washington Post.

The actions took a curious turn when Sherwin, acting in his position as U.S. Attorney at Trump's discretion, came to the defense of Black Lives Matter protestors that DC Mayor Muriel Bowser wanted charged with crimes.

[18][19] In June 2020, Sherwin closed a three-year-long investigation into whether a state-owned Egyptian bank had secretly financed a $10 million loan by Trump to his political campaign in the days shortly before the 2016 presidential election.

[20][21] In December 2020, Sherwin charged bombmaker Abu Agila Mas’ud in a criminal complaint with designing and building the bomb which took down Pan Am Flight 103 in 1988 over Lockerbie, Scotland, killing all 270 people aboard.

Through March 2021, Sherwin supervised the early months of investigations into the 2021 storming of the United States Capitol charging 325 individuals.

[22][23] The Biden administration and, later, Attorney General Merrick Garland asked Sherwin to stay on at the Justice Department in another role to continue the prosecutions.