Answer :

Assuming you're talking about the US justice system . . . individuals still have rights when they are accused of criminal acts because our justice system requires that each individual be innocent until proven guilty in a court of law. Until such point that they are proven guilty, they are assumed innocent, and are entitled to the same rights as you or I am, having not committed any criminal acts. . . . THEY HAVE TO BE PROVEN GUILTY FIRST BEFORE THEY LOSE ANY RIGHTS AS A CITIZEN
All individuals have rights whenever they are accused of wrongdoings because it has to be fair for them too.
Say there is a man named John who is accused of murder, but he never actually commited the murder and the real murderer set him up. If John didn't have rights for this and the people executed/or jailed him without hearing him out, then justice wouldn't be served.
Hope this helps!