You are an investigator who investigates an alleged robbery with homicide case perpetrated by an unknown suspect. Since there are no witnesses to the crime the following may give you a hint to identify the suspect, except one.
a. Modus Operandi, associative evidence and criminal potentiality
b. Declaration and acts indicative of guilt, preparation for a commission of crime and possession of fruits of a crime of the perpetrator
c. Knowledge, skills, tools or facilities that could easily be adopted to criminal use by the suspect
d. Motive and opportunity​