An extension of How does one find a judge for highly publicized issues?
The answer to that question says that judges can adjudicate a case even if they had prior knowledge of the facts, and can be trusted to do so fairly because they are trained not to let their prior prejudices influence their rulings.
What if a highly-publicized trial is to be decided by jury instead - how would one find an unbiased jury?
Looking at Wikipedia's article on jury selection, it seems to say that both the prosecution and the defense can object to a jury member, and often they don't even have to give reasons; however they only have a certain number of possible challenges. In other words, if all the originally-selected jury members have heard of the event and possibly already formed an opinion, one is indeed stuck with biased jurors - which seems less than ideal.