CHICAGO (AP) _ Imprisoned El Rukn street gang leader Jeff Fort and five of his top officers have been indicted for a 1981 slaying, and authorities say the new charges show that the organization is beginning to crumble.

''The El Rukns are now in disarray, and much of their power has eroded,'' Cook County State's Attorney Richard M. Daley said after the indictments were announced Wednesday.

If convicted, the six could face prison sentences of 20 to 80 years.

The charges resulted from an attack on a South Side bar, allegedly ordered by Fort, in which Willie ''Dollar Bill'' Bibbs was shot to death, authorities said. They said the attack was part of a struggle over drug-dealing territory.

Ernest DiBenedetto, chief of Daley's gang-crimes unit, said Wednesday's indictments were the result of El Rukn unity cracking under the pressure of dozens of convictions over the past several years.

DiBenedetto said information leading to the indictments came from several people ''who didn't want to share their information in the past.''

''When the organization starts crumbling, it makes them start thinking a little bit,' DiBenedetto said.

Fort is awaiting trial, along with five other reputed El Rukn members, for allegedly offering to carry out terrorist attacks in the United States in exchange for funding from the Libyan government, said Assistant U.S. Attorney Patrick E. Deady.

Fort is imprisoned at the federal penitentiary in Marion, where he is serving concurrent 13-year and 15-year sentences for narcotics convictions.

Indictments were also handed down Wednesday against 31 other reputed El Rukn members on charges of delivering a controlled substance, Ms. Howard said.

All 37 are to be arraigned Aug. 4 before Chief Criminal Court Judge Richard Fitzgerald in Chicago.

Fort began the gang two decades ago as the Blackstone Rangers and later changed the name to the Black P Stone Nation. The group became the El Rukns when Fort decided to adopt a quasi-Islamic religious cover for the gang's activities, police say.