Acro was racked with guilt for his crime. Instead of killing the intended target, he had killed the ringmaster, who had shown him nothing but kindness and generosity.

Who murdered the ringmaster?

Acro's anger towards Regina eventually led him to devise a plan to kill her six months after the incident with the lion. However, this resulted in the death of Russell Berry, the ringmaster, instead. The resulting trial of Max Galactica led to Acro's implication as the killer by Phoenix Wright.

Did Acro have an accomplice?

Von Karma now suspects you will try to claim that Acro had an accomplice. When given a choice, choose Of course he didn't. Acro committed the murder all by himself. When you are asked where he committed the crime, on the circus map, Present Acro's Room (3F).