See if i can remember the Latin,

1. Mens Rea or guilty mind is the intention or knowledge of wrongdoing that constitutes part of a crime, or as you have kindly put "intent"
2. Actus Reus is the Latin term used to describe a criminal act. Every crime must be considered in two parts-the physical act of the crime (actus reus) and the mental intent to do the crime (mens rea) and finally
3. Corpus Delecti or "body of proof" which could be a dead body if the crime was murder.
   i believe all 3 must be proved in common law. Please check definition of Actus Reus in a dictionary, this should help.