CHICAGO -- 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. He was 78.

Schweihs, who had cancer , died Wednesday night after he was taken from the federal government's Metropolitan Correctional Center to Thorek Memorial Hospital, authorities said. He had been in federal custody for more than two years.

Prosecutors said Schweihs was responsible for killing two people: a Phoenix man who 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.

Federal law enforcement officials said Schweihs specialized in beatings and murders, and they had hoped to put him in prison for life. His trial was scheduled to begin on Oct. 28.

Prosecutors had hoped to try Schweihs along with five others in a landmark mob conspiracy trial last fall, but he was deemed too ill to take part.