If you are arrested for a crime that you did not commit, you may not be too worried about proving your innocence. Since you know that you did not commit the crime, you may feel that it will be obvious to a court that you have done nothing to justify a conviction. Going into a case this way is dangerous, because if you are too careless you may still be convicted.
There are plenty of people imprisoned by the legal system who are innocent. Some of these wrongful convictions come from mistakes in eyewitness testimony or different physical evidence that was presented. The best way to protect yourself from being convicted is to hire a powerful legal team and make sure that they build you a strong defense.