Numerous other Lincoln assassination conspiracy theories exist. Two of the most interesting, albeit incredible, involve Andrew Johnson and the papacy. Members of Congress tried to implicate Andrew Johnson in the assassination. They even called a special committee to investigate in 1867. The committee could not find any links between Johnson and the killing. It is interesting to note that Congress impeached Johnson that same year.
The second theory as proposed by Emmett McLoughlin and others is that the Roman Catholic Church had reason to hate Abraham Lincoln. This is based on Lincoln's legal defense of a former Priest against the Bishop of Chicago. This theory is further enhanced by the fact that the Catholic John H. Surratt, the son of Mary Surratt, fled America and ended up in the Vatican. However, the evidence connecting Pope Pius IX with the assassination is dubious at best.
The assassination of Abraham Lincoln has gone through many revisions during the past 136 years. Immediately following the tragedy, the Grand Conspiracy involving the Confederate leaders was the most widely accepted. Around the turn of the century, the Simple Conspiracy theory had gained a position of prominence. In the 1930's, Eisenschiml's Grand Conspiracy theory arose with the publication of Why Was Lincoln Murdered? In addition, the years have been sprinkled with other outlandish conspiracies to explain the assassination. As time has passed, one thing is true, Lincoln has become and will remain an American icon lauded with an impressive strength of will and given credit for saving our nation from division and moral oblivion.
Citation: Hanchett, William. The Lincoln Murder Conspiracies. Chicago: University of Illinois Press, 1983.