What evidence is neccesary to make a vandalsim charge?

Although I do not practice law in the State of Kansas, here are my initial impressions.  The general rule is that there is no "specific" kind of evidence required to charge someone with any crime.  Any type of evidence, whether it is direct or circumstantial, can be used to charge someone.  As long as the evidence provides probable cause to establish that the suspect committed the crime, it is sufficient to charge the person.  Based upon the facts that you have provided, an eyewitness statement is probably sufficient to establish probable cause.