Lyndon Johnson and Mac Wallace crossed paths only briefly; but Wallace's life, especially one violent episode and its intricate aftermath, illuminates the dark side of our 36th president.Perhaps no president has a more ambiguous reputation than LBJ. A brilliant tactician, he maneuvered colleagues and turned bills into law better than anyone. But he was trailed by a legacy of underhanded dealings, from his "stolen" Senate election in 1948 to kickbacks he artfully concealed from deals engineered with Texas wheeler-dealer Billie Sol Estes and defense contractors like his longtime supporter Brown & Root. On the verge of investigation, Johnson was reprieved when he became president upon JFK's assassination. Among the remaining mysteries has been LBJ's relationship to Mac Wallace who, in 1951, shot a Texas man having an affair with LBJ's loose-cannon sister Josefa, also Wallace's lover. When arrested, Wallace cooly said "I work for Johnson . . . I need to get back to Washington." Charged with murder, he was overnight defended by LBJ's powerful lawyer John Cofer, and though convicted, amazingly received a suspended sentence. He then got high-security clearance from LBJ friend and defense contractor D.H. Byrd, which the Office of Naval Intelligence tried to revoke for 11 years without success. Using crucialLifemagazine and Naval Intelligence files and the unredacted FBI files on Mac Wallace, never before utilized by others, investigative writer Joan Mellen skillfully connects these two disparate Texas lives and lends stark credence to the dark side of Lyndon Johnson that has largely gone unsubstantiated.