If you charge someone with misdeeds or misconduct, you accuse that person. If the last piece of devil's food cake is missing, your sister may accuse you of eating it — especially if you have chocolate on your mouth.
The verb accuse comes from the Latin word accusare, which itself is formed from the roots ad, meaning toward, and causa, reason or lawsuit. "Cause," "excuse," and even "ruse" are all from that same root word. Today, if you're accused of a crime, you may still be headed toward a lawsuit. However, to accuse someone of a crime doesn't necessarily make them guilty — plenty of people have been falsely accused.