The court in Dusseldorf said it was convinced the accused, 36, had been a member of DHKP-C, a violent Marxist group, and taken part in a campaign in 1997 to hunt down and harm renegade members in the German city of Hamburg.
No one was actually hurt. The group broke off the hunt after a week after failing to catch the former members. But the leftists might have killed someone, presiding judge Barbara Havliza said.
He was also convicted of conspiracy to commit manslaughter.
The verdict closes the first of four Dusseldorf trials of militants in DHKP-C. The group has been outlawed in Germany since 1998.
Dusseldorf - DPA