It depends on what the trial was about and where it was held. I know that the AARC Public Library holds some trial transcipts for US cases and CNN.com holds some. Your best bet is to try googling the name of the accused followed by trial transcipt and news paper sites etc will be able to let you know about the transcipts online. If you want it in person your best bet is to contact the clerk of the court where the trial was held and they can tell you where the transcipts are available to view.
If the trial took place in England/Wales you should be able to get a transcript but you will have to pay for it. There is a company called Cater Walsh in Kiddermininster who are court transcribers but I dont know if they cover the whole country or just a region
Unless you particularly need a transcript it may be best to simply try the local papers for press coverage at the time