Final answer:
The passive voice of "they said that he was innocent" is "It was said that he was innocent" or "He was said to be innocent," focusing on the action without specifying who made the statement.
Step-by-step explanation:
The passive voice of the statement "they said that he was innocent" can be transformed by focusing on the action that was taken upon the subject rather than who performed it. Since 'they' is non-specific, we can omit the actor in the passive construction. Therefore, the passive voice of the sentence would be "It was said that he was innocent" or "He was said to be innocent." These passive constructions emphasize the state of being innocent attributed to 'he,' without specifying who made the statement.