Definition: In this task, you will be presented with a passage and have to answer a question based on your understanding of the events inferred from the passage. Try to find the best answer that is most likely to fill in "_". Note that the URLs in the text have been replaced with [Link].
Input: Victim: Dr Martin Luther King The FBI repeatedly deceived Congress by destroying vital files relating to the assassination of Martin Luther King, a new book claims. Leading King historian Stuart Wexler said that the bureau chose to cover up the potential role of a high level informant in the killing rather than tell the truth. Wexler said that it could have been one of the greatest scandals in the history of the FBI - but now we may never know what happened. By destroying the files the FBI disobeyed a direct order not to do so from a Congressional Committee which had been set up to investigate the killing of King and former President John F Kennedy.FBI accused in new book - by leading King historian Stuart Wexler - of misleading Congress by destroying files on civil rights leader's murderHe tells Daily Mail Online agency disobeyed direct order to preserve all materials and believes it was to protect informer from being identifiedTommy Tarrants, high-ranking KKK member went from being little-known racist to having his picture shown to witnessesFiles from two field offices which had information on Tarrants were destroyed in 1977 after Congress launched Assassinations CommitteeWexler believes it is because they could have exposed Laude Matthews, head of Mississippi KKK, as an FBI asset under deep cover 
 Question:'They wanted _ to give evidence to the committee, they didn't want him to be a suspect.

Tommy Tarrants