Why, Mark David Chapman, of course--but the hook here is that British attorney Bresler (The Chinese Mafia, 1980; The Mystery of Georges Simenon, 1983) believes that Chapman may have been a kind of ""Manchurian Candidate,"" a programmed assassin who killed Lennon on CIA orders. ""The telephone rings. He picks it up. A Familiar voice says, 'Do it, do it, do it!'--and rings off."" So runs a snippet of Bresler's fearfully imaginative scenario that has the CIA puppet-mastering Chapman into gunning down the fir met Beatle. How did Bresler drum this up? By adding 2 and 2 and getting 5; i.e., by tracing Lennon's destroy, and Chapman's, and finding in the collision of the two a sign of conspiracy. True, as Bresler documents, the FBI and the CIA had been tracking and harassing Lennon for years because of his radical politics, and true, Chapman--who never evinced an understandable motive for killing Lennon--did spend a lot of time at YMCAs, which may have some link to the CIA, and did boast unknown sources of income. But Bresler's furious investigating leaps from the sensible--an attack on Albert Goldman's sloppy investigation--to the ridiculous; noting that Chapman wrote ""To Dorothy"" on a Wizard of Oz poster, Bresler asks, ""Why Dorothy? Only homosexuals venerate the character so much. . ."" And so, making much of Chapman's Catcher in the Rye-identification (""The telephone rings. . .He wakes up. . .and hears: 'Catcher, Catcher, Catcher!' "") and little of the killer's media-alleged Lennon-identification, Bresler weaves his fairy tale. He does finally admit, however, that Chapman recently wrote to him, denying any conspiracy--but ""he could long ago have been programmed into complete memory-loss."" Preposterous--but not useless, with some able detailing of Chapman's life and the government campaign against Lennon, and with a rare update on Chapman in prison: confined to a ten-by-seven-foot cell, he's now a born-again Christian.