Are you confusing the term 'prisoner' with 'criminal'? Prisoner is used to refer to people waiting for trial frequently, and dictionaries seem to support this definition.
Perhaps you have a different term besides "prisoner" to describe someone who is imprisoned before their trial rather than after. But the parent comment is correct: whatever you call them, these people are not afforded all of the rights that the rest of us have.
This is the truth. The legal exception is literally carved out in the 13th amendment; the government reserved the right to make slaves of its prisoners.