Log On to the Dark Side

When a knife-wielding madman attacked and killed eight children at an Elite elementary school in Ikeda, some Internet users in Japan had a sinking feeling. Six days before the bloody rampage on June 8, visitors to a popular bulletin board server called Channel 2 had seen an ominous rant. "My pride has been destroyed. I hate university-affiliated schools," the anonymous writer raged. "Some may say my anger is misplaced and misdirected, but it's all their fault. I am very vindictive."

Could the chilling note have been written by Mamoru Takuma, the 37-year-old man police say confessed to the...