Chief of FBI’s Jet Crash Probe to Retire

James K. Kallstrom, who led the FBI’s probe into the explosion of TWA Flight 800 and helped bring down scores of organized-crime figures in a 28-year career, said Tuesday that he will retire at the end of the month.

“I have to take care of my family and make sure my daughters are educated properly,” said Kallstrom, an assistant director and chief of the agency’s New York office. Kallstrom, 54, said he will join MBNA Inc., a bank and credit card firm based in Wilmington, Del.