With criminal law there are generally two elements involved ... the actus reus (criminal act) and the mens rea (criminal intent). Generally there is no crime unless both are involved. Mens rea is a slippery term though. Most criminal law is statutory in nature, and the mens rea may be satisfied by knowledge of the wrong doing or evil intent...depending on the statute.  In some cases negligence is all that may be required .. as in the case of  involuntary manslaughter.

There is a dichotomy in criminal law and civil law that is a relatively recent development in the past two hundred years. Some conduct which once may have been deemed to be criminal is more properly classed as a civil matter by today's standards. Our law is derived from an English system of justice. However, in merry  old England they were still hanging hungry children for stealing a loaf of bread well into the 1700's, and debtor's prisons were common place. In the witch trials of earlier centuries there was little distinction between humans and animals, and it was not unusual for a woman accused of witchcraft to be executed along with her pet cat because the cat was deemed to be a demonic familiar. I remember reading one case from medieval Europe in which a cow was hung on the gallows next to its alleged criminal co-conspirator.