The most appropriate word to fill in the blank is confess.

The word confess means to admit to having done something wrong. In this context, the speaker is asking the listener to admit to having committed a crime.

The other words do not fit the blank as well.

• Apologize means to express regret for something that one has done wrong.
• Agree means to have the same opinion about something.
• Pardon means to forgive or excuse (a person, error, or offence).