Frank "The German" Schweihs, reputedly one of Chicago's most feared mob enforcers, has died while awaiting trial on charges he took part in a conspiracy that included numerous organized crime murders.

Schweihs, 78, who had cancer, died Wednesday night after he was taken from the federal government's Metropolitan Correctional Center to Thorek Memorial Hospital, federal officials announced Thursday.

He had been in federal custody for more than two years.

Federal law enforcement officials said Schweihs specialized in beatings and murders, and they had hoped to put him in prison for life.

"It means that we have one less brutal and cowardly outfit enforcer to worry about and we can move on," said Markus Funk, an assistant U.S. attorney at last fall's landmark mob conspiracy trial.

Funk, who helped secure racketeering convictions against five major mob figures at the trial, was due to prosecute Schweihs on similar charges starting Oct. 28.

Prosecutors had hoped to try Schweihs along with the five others last fall, during one of the biggest mob trials in Chicago history. But Schweihs was deemed too ill to take part.

He went to New York for cancer treatment last year and recently returned to the Metropolitan Correctional Center to await trial.

The indictment charged that the conspiracy included 18 long unsolved mob murders. Prosecutors said Schweihs was responsible for killing two people: a Phoenix man that mobsters deemed a potential federal witness and a suburban Chicago businessman who had evidence that might have sent another mobster to prison.

Star witness Nicholas Calabrese, brother of one of the defendants, testified Schweihs came up with the idea of using an Uzi submachine gun to murder Tony "The Ant" Spilotro, the Chicago mob's longtime man in Las Vegas.

Spilotro was the inspiration for the Joe Pesci character in the movie "Casino."

Calabrese said the Schweihs plan called for gunning down Spilotro, his brother Michael and defense attorney Oscar Goodman. The plan fell through.

But both Spilotros were later killed somewhere in the Chicago area and buried in an Indiana cornfield. Goodman is now the mayor of Las Vegas.