A teenager who admitted plotting a school attack near Philadelphia had chatted online about a famous US school massacre with a teenage outcast in Finland who later killed eight people and himself in a high school shooting, the American boy's lawyer said Monday. Finnish police said material seized from the computer of Pekka-Eric Auvinen suggests the 18-year-old had communicated online with Dillon Cossey, 14, who was arrested in October for allegedly preparing an attack at Plymouth Whitemarsh High School in suburban Philadelphia. Cossey's attorney, J. David Farrell, said he showed Auvinen's online screen name to his client Monday and the teen remembered communicating with him about video games and the 1999 Columbine massacre in Colorado, in which two students killed 13 people before fatally shooting themselves. The two also exchanged videos they found on the Internet. "They had discussed certain video games and shared videos with each other," Farrell said. "Obviously, Columbine was a shared topic of interest." But Cossey was "horrified" when he found out about the attack in Finland, and said he never would have suspected Auvinen of following through on a violent act, Farrell said. "My client didn't encourage him in any way," Farrell said. "He had no indication that somebody he was communicating with actually was formulating an intent to commit a violent act." Auvinen killed six students, a nurse and the principal Wednesday in Tuusula, about 30 miles (48 kilometers) north of the Finnish capital, Helsinki. He then shot himself in the head, and died hours later at a hospital. Finnish investigators have said Auvinen left a suicide note for his family and foreshadowed the attack in YouTube postings. On Monday, Rabbe von Hertzen, a detective in the case, said Auvinen is believed to have written the suicide note on Nov. 5, suggesting he had planned the attacks for at least two days. Police have described Auvinen as a bullied teenage outcast consumed with anger against society.