George Joannides played a crucial role in obstructing investigations into Lee Harvey Oswald and his connections prior to JFK's assassination. As a CIA liaison to the House Select Committee on Assassinations (HSCA), Joannides deliberately withheld information from investigators about Oswald's interactions with anti-Castro groups like the Directorio Revolucionario Estudiantil (DRE). By impeding access to key documents and providing limited cooperation, Joannides prevented HSCA researchers from uncovering potentially incriminating evidence that could have shed light on Oswald's activities leading up to the assassination. His actions raised suspicions of CIA involvement or complicity in suppressing vital information related to Kennedy's murder.