When you were twelve you started hearing voices. They were distant at first but grew louder with time. After several long stays in psychiatric hospitals, many therapists, and a lot of strong prescription medicine, you learn the truth. These are sounds you will hear at an unspecified point in the future.
As you slowly master your strange ability, you learn that it comes with many advantages. Knowing things ahead of time can be very useful. If you focus you can leave your past self messages.
Guided by your older and slightly wiser self, life becomes easy. One day, you hear your voice saying, “I didn’t mean to kill him.”
The next voice says, “I am arresting you on suspicion of murder. You do not need to say anything but…”