Complex sentence: In 1968, kidnapped by Red Guards and "tried" by their "court" for his poetry-society activity years before he jumped out of the window of the third-floor room where he was held and died at the age of 26.
Split into simpler sentences: In 1968, kidnapped by the Red Guards and "tried" by their "court" for his poetry-society activity years ago. Jumped out of the window of the third-floor room where he was kept, and died, at the age of 26.