The 5th Amendment protections can be used even if someone has nothing to hide and is innocent of any crime. A person's words and admissions can be used against them even if they did nothing wrong. It is the prosecutor's job to get enough evidence to prove beyond a reasonable doubt that the suspect is guilty of a crime. The suspect does not need to be the one that gives the prosecutor any evidence against their own self-interest.
EXAMPLE OF PLEADING THE FIFTH
Jake broke into Sarah's house to take back his computer that she would not return to him. Jake left with his computer and went home. Later, Sarah's house had burned down after a candle that had been left burning unattended.
The police knock on Jake's door and tell him they want to ask him some questions. Jake says he wants to have his lawyer present before he answers any questions. Jake and his lawyer sit down to talk to the police.
The police ask Jake if he was at Sarah's house. Jake did not want to admit that he had broken into Sarah's house because he was worried that he would be prosecuted for burglary. When the police ask Jake if he was at Sarah's house, Jake responds, “on the advice of my lawyer, I invoke my 5th Amendment privilege against self-incrimination.”
Jake can plead the 5th even though he is innocent of burning down the house. The police may suspect Jake of arson. If Jake responded that he was at the house but did not start a fire, the police may charge Jake with arson even though he is innocent of that crime. If the police did not know about taking the computer, Jake admitting to it could also result in prosecution for
burglary.