How many staff members were taken hostage during the prision riot that David Rothenberg was a civilian observer of?
David Rothenberg (activist):  Later, he was a civilian observer during the Attica Prison riot which left a deep impression on him and spurred his lifelong activism for prisoner's rights. Attica Prison riot:  On September 9, 1971, two weeks after the killing of George Jackson at San Quentin State Prison, about 1,000 of the Attica prison's approximately 2,200 inmates rioted and took control of the prison, taking 42 staff hostage.
42