William J. Martin, the prosecutor turned criminal-defense lawyer turned lawyer’s lawyer who once earned a death-penalty verdict against Richard Speck, died Friday at the age of 80.As a 29-year-old with the state’s attorney’s office, Martin represented the people’s case against a man who, in 1966, broke into a townhouse and systematically tortured, raped and murdered eight sleeping student nurses inside.“He wasn’t 30 years old yet, and he was the lead counsel on the Speck case,&rdquo …