Cory @ comment 16:

Bobby Seale gave two speeches in Chicago in August '68. He was not an organizer and he was a late replacement for (I think) Eldridge Cleaver, but those were significant speeches. Significant enough, provocative enough, and actionable enough to make Seale irresistible to federal prosecutors.

He was in the indictment and trial because his words were the most inflammatory ones spoken during Chicago '68. So, at the trial, his speeches were introduced into evidence, then he was bound and gagged, and then he was severed from the trial. Neat, huh?

The government got the Seale words into the trial without, in the end, having to deal with the racial issues crated by prosecuting him. There were aspects of Seale's role in the trial that accidentally but actually worked to the advantage of the prosecution.

The publisher of The Deep, the University of Chicago Press, has a much more substantial gallery of photos on its website for the book.