One motive that has been suggested for Lyndon B. Johnson (LBJ) potentially being involved in the assassination of John F. Kennedy (JFK) involves political ambition and self-preservation. At the time of Kennedy's assassination, LBJ was embroiled in several political scandals that could have led to his downfall. He was known to be facing investigations related to his financial dealings, particularly around the Bobby Baker scandal and the Billie Sol Estes case, which could have resulted in criminal charges against him. If these scandals had come to light in full force, it might have ended his political career or even led to legal action. By becoming president upon Kennedy's death, Johnson not only escaped potential political ruin but also gained the ultimate position of power in the U.S. government, thereby securing his legacy and influence.
 

Another reason posited for LBJ's possible involvement centers around his strained relationship with the Kennedy brothers, particularly Robert F. Kennedy, who was the Attorney General. There were reports of personal animosity between LBJ and RFK, with Robert Kennedy known to be investigating the aforementioned scandals linked to Johnson. This dynamic could have provided Johnson with a motive to eliminate JFK, who was seen as grooming his brother for higher office, potentially sidelining or even prosecuting Johnson. With JFK out of the picture, the path to the presidency was clear for Johnson, and he could steer the direction of any investigations or political maneuvers against him.
 

Finally, LBJ's desire to control and shape U.S. policy, especially in areas like Vietnam and civil rights, might have played a role. Kennedy's approach to the Vietnam conflict was more nuanced and less aggressive than what Johnson would later adopt, which led to the escalation of U.S. involvement in Vietnam. Some conspiracy theories suggest that factions within the U.S. government, including elements of the military-industrial complex, were dissatisfied with Kennedy's policies, particularly his reluctance to engage more aggressively in Vietnam. Johnson, known for his legislative prowess and willingness to push through significant policy changes, might have seen the assassination as an opportunity to implement his vision for America, both domestically and abroad, without the constraints of Kennedy's more measured approach. These theories, while speculative, are part of a broader discourse on the Kennedy assassination that includes examining the power dynamics and political motivations of the time.