NIGHTWISH mainman Tuomas Holopainen (keyboards) spoke to the Finnish News Agency (STT) about the group's decision to fire their lead singer, Tarja Turunen, following the final show of their "Once" world tour, which took place on Friday, Oct. 21 at Helsinki's Hartwall arena.Holopainen told STT that the "open letter" on the band's web site contained all the details about the split with Tarja that the band wanted to make public at this time. "A NIGHTWISH book will be published in May. In it, the reasons for the split will be examined in more detail," Holopainen said. He added that he and Turunen had not spoken since the letter was posted. "I have not spoken with Tarja, but then again we have not spoken with each other for many years," he said. "We all know that personal relationships are the most difficult thing in the world. All couples have their problems, and after all, there are five of us in this band." Tuomas did not wish to comment on who the new singer might be. Holopainen, who is responsible for most of the songwriting in NIGHTWISH, said in the group's open letter that Turunen had concentrated on business at the expense of music and friendship. "To you, unfortunately, business, money and things that have nothing to do with those emotions have become much more important," the letter reads. "You feel that you have sacrificed yourself and your musical career for NIGHTWISH, rather than thinking what it has given to you. "You have said yourself that you are merely a 'guest musician' in NIGHTWISH. Now that visit ends and we will continue NIGHTWISH with a new female vocalist." Turunen has studied classical singing at the Sibelius Academy in Finland and at the Karsruhe University of Music in Germany.