You are a member of the FBI's special task force as a forensic scientist.

A few months ago,the special task force solved a major case.The criminal was the most brutal cannibalistic murderer of the decade.He even challenged William,the world's most talented psychology expert,who is also your boss.

Today,the special task force received a case in the city center.Because the crime scene was extremely brutal,showing that the murderer was a psychopath,the local police immediately invited Professor William's special task force.

Everyone immediately went to the scene. You examined the body and judged the time of death.William walked around to examine the scene.The other members investigated the surroundings.Suddenly someone shouted,the members immediately raised their heads,seeing a line of blood on the wall:

"Hi,William."

Everyone immediately fell silent, they were too familiar with this type of writing.The murderer they caught a few months ago had also challenged William like this.Could it be that there was more than one cannibal killer?