The efforts of the FBI to solve this case were certainly in the greater good, and they did solve the case, even though the trial was a mockery. It seems the FBI could have done more to have the case moved to a more neutral location to help ensure a fair trial, which certainly did not happen. Indeed, the FBI gave high priority to the case, and even opened an office in Mississippi during the investigation (Editors). It is difficult to see how they could have done more. Not all of their decisions were ethical, but neither was the decision to murder three young men simply because of their convictions.

Was every action ethical? No, they literally paid for confessions and the safety of those who confessed. However, they were dealing with terrorists, and to reach them, they had to think like them, act like them, and do whatever they could to catch them. They threaten the mayor with castration, state a mock execution, and use all kinds of terrorist tactics of their own to gain the truth. They must act...

Their efforts were certainly not ethical, or even fair, but neither were the murders. Their actions were justified, because ultimately, they did save lives and some clansmen were convicted and served jail terms (Editors). However, not all the people responsible were initially tried, and another defendant, Edgar Ray Killen, was recently convicted of the murder as well. Did the FBI do everything right? No, they did not, but they caught the people responsible for this terrible murder, and hopefully kept at least some of them from murdering others, and that justified their unethical behavior.
References

Editors. (2006). Famous American trials: U.S. Vs. Cecil Price, et al. Retrieved from the University of Missouri-Kansas City Web site: http://www.law.umkc.edu/faculty/projects/ftrials/price&bowers/price&bowers.htm2 April 2007.

Mississippi Burning (1988). Dir. Alan Parker. Perf. Gene Hackman, William Dafoe. Hollywood: Orion Pictures.