MINNEAPOLIS — A former head of the Minneapolis FBI office sent federal lawmakers a letter Thursday sharply criticizing President Barack Obama’s nominee to lead the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives, calling B. Todd Jones an ineffective leader who consistently declined to prosecute violent gang, drug and gun crimes.

Donald Oswald, a former special agent in charge in Minneapolis, said in the letter mailed to Senate Judiciary Committee members that he felt morally compelled to share what he called Jones’ “atrocious professional reputation” among Minnesota law enforcement. Oswald said he felt he could speak out because he has retired, while active law enforcement authorities might fear retaliation.

“When I learned on TV that Todd Jones had been nominated by the president for ATF director, I reacted physically ill to it and it bothered me for several days until I decided I had to do something, and I had to put this letter forward to reveal exactly what kind of a leader he is,” Oswald said in an interview with The Associated Press.