Clark Perry Baldwin, 59, of Waterloo, Iowa, was arrested by agents with the Wyoming Division of Criminal Investigation and Federal Bureau of Investigation.
Bruce Sloyer's preliminary hearing is scheduled for Oct. 4, during which the state will try to show there is probable cause that his case should be bound over for trial.
Lamb was arrested and charged with murder in the first degree and arson in the first degree in connection with the 1985 slaying of University of Wyoming student Shelli Wiley.