An FBI spokeswoman says the head of the agency's office in Chicago is retiring after about seven months on the job.
The more than 20-year FBI veteran, Cory B. Nelson, assumed the post in January.
The spokeswoman, Joan Hyde, said in an email Thursday evening that Nelson is leaving. She didn't immediately offer details.
The Chicago office is considered one of the highest-profile FBI offices in the country, handling everything from political corruption to terrorism cases.
The 51-year-old Nelson replaced Robert Grant, who retired in September after more than seven years as the special agent in charge of the Chicago office.
Grant left to take a global-security position with Walt Disney Co. in Los Angeles.