Clark also waived his right to a probable cause hearing at which prosecutors would have to prove they have enough evidence to justify the murder charge.
Clark is accused of killing 24-year-old Annie Le of Placerville, Calif. Her body was found behind a Yale research lab wall in September. An autopsy determined she was strangled.
Le vanished Sept. 8 from the Yale medical school research building where she and Clark worked. Her body was found five days later, on what was to have been her wedding day.