The FBI said Thursday that an agent who had been helping oversee the federal investigations into political corruption in the District has been promoted.

Ronald Hosko, who ran the criminal division of the bureau's Washington field office and regularly spoke at news conferences detailing investigators' triumphs, will become an assistant director of the FBI.

Hosko, who joined the FBI in 1984, will oversee all of the FBI's criminal investigations.

Hosko is exiting the Washington field office as it continues probes of D.C. Mayor Vincent Gray's 2010 campaign and the 2008 campaign of former D.C. Council Chairman Kwame Brown. Authorities are also investigating thefts from the Children and Youth Investment Trust Corp. by former Ward 5 Councilman Harry Thomas Jr., who is now serving a prison term, and the possibility of bribes linked to the D.C. lottery contract.

A spokeswoman for the FBI said the bureau has not yet named a replacement for Hosko, who is expected to begin his new role within weeks.