What happened to three of the ten death row prisoners in the analogy?
In the analogy, the governor issued a decree pardoning three of the ten death row prisoners. Those three were selected at random, given their pardon, and sent home as free men, though they were just as guilty as the remaining seven.
Les explains that ten men were sitting on death row in a state penitentiary, all convicted of nearly identical murders and awaiting the death sentence. In the midst of their waiting, the governor sent down a decree that pardoned three of the ten. Those three were picked out, given their pardon, and sent home free. The other seven could not demand release, because they were still guilty murderers deserving death. The three did not deserve freedom either, being just as guilty, but they were set free by the grace of somebody—the governor or the warden.