John and Patsy Ramsey have broken their long silence on the murder of their daughter JonBenet and are talking at length to a London production company that plans to air an hour-long documentary on Britain's Channel 4. Producer David Mills is also discussing a deal that will get the show aired in the U.S. Mills and his partner, University of Colorado journalism professor Michael Tracey, bill the interview as a no-holds-barred session, in which no questions went unanswered. If so, this will be remarkable, given the Ramseys' reluctance to talk to anyone, including the Boulder, Colo., police. The producers say the documentary will debunk certain assumptions, among them that JonBenet had been sexually abused, and offer new support for an outside-intruder theory. Notwithstanding the claim that the family had no editorial control, it is difficult to see how the show can fail to boost the Ramseys' fortunes. It is likely to air in spring or early summer -- about the time that a grand jury may investigate the murder.