A bank embezzler who turned himself in two weeks ago shortly after being declared legally dead was killed yesterday in a fiery plane crash as he prepared to lead FBI agents to $50,000 in stolen cash buried somewhere in Cincinnati.

Four FBI agents and a Chicago bank detective also were killed as their chartered two-engine plane, approaching Cincinnati's municipal airport, struck a telephone pole and exploded in a fireball as it crashed into a bookstore in a three-story building in the suburb of Montgomery.

The crash was the worst disaster in the history of the FBI.

The bureau had never lost four agents in a single operation before, according to Alfred E. Smith, special agent in charge of the Cincinnati FBI office. "This hits home," Smith said.

Knowledge of the location of the $50,000, part of $615,000 embezzled from a Chicago bank seven years ago, apparently disappeared in the crash.

Killed with embezzler Carl Henry Johnson, 46, were FBI special agents Terry B. Hereford, 34, Wheaton, Ill.; Robert W. Conners, 36, Naperville, Ill.; Michael J. Lynch, 35, Woodridge, Ill., and Charles L. Ellington, 36, Naperville, Ill., and Patrick Daly, 68, a retired policeman and bank detective from Evergreen Park, Ill.

Police said at least four people in the bookstore were injured, two critically.

The building, a converted three-story frame house, collapsed. Firemen battled the blaze for more than two hours.

The plane was piloted by Conners and Hereford.

Witnesses said the Cessna 411 "made a real funny noise" and tore through power lines before flipping over into the bookstore.

Johnson turned himself in to federal authorities in Chicago Dec. 2, shortly after his wife had him declared dead at the end of the legal waiting period of seven years.

He told authorities he had "had enough" after seven years on the run.

Johnson, assistant comptroller of the National Bank of Albany Park in Chicago, disappeared Aug. 6, 1975.

The next day the bank discovered that $615,000 also had disappeared.

The FBI quickly recovered $144,000 that Johnson left with his parents and in the pew of a Chicago church.

But from that point on the authorities drew a blank.

Last Friday Johnson led FBI agents to $50,000 he had stashed in a remote forest preserve in northwest Chicago.

He had promised to lead them to another $50,000 he had buried in a remote stash somewhere near Cincinnati.

When he turned himself in, Johnson had no idea he had been declared legally dead so that his wife, a schoolteacher who now lives in Lakeland, Fla., could collect $22,500 in life insurance. They were estranged at the time of the embezzlement.

Federal agents had searched for Johnson throughout the world, often focusing on countries such as Zimbabwe which have no extradition agreements with the United States.

As it turned out, Johnson spent most of the time in San Diego and mostly "feeling cowardly and scared."

When he turned himself in, he was accompanied by a lawyer and a minister.

Officials in Cincinnati said they have no clue to the cause of the crash.

Air traffic controllers at Greater Cincinnati Airport in Florence, Ky., said they tracked the six-seat Cessna on radar until about 10:30 a.m., when it dropped out of sight.