. Jim Muth wrote:

....if one went back in time and killed his earlier self, would he be guilty of homicide or suicide?

You can not go back in time and kill yourself (or your ancestors) because you would then not have ever existed in the first place to make the attempt. If a time travel method was developed and you did set out to do this, some how, some WAY your effort would (would have) failed. Because it has "already happened". The so called time travel paradox really isn't (as I see it). Cool to ponder however ..... .