do horror films turn people into killers?

horror film "scream" has been blamed for a number of copycat murders. In nov 2001 a belgian lorry driver was accused of killin a teenage girl while wearin a scream costume, he later confessed the murder ad been motivated by the film. After the Virginian Tech massacre in the US last year, killer Cho Seung-Hui sent pictures of himself to the media, posin as characters from the South Korean film Oldboy. In the summer of 2007 the Izaga family led a normal normal life till Alberto brutaly murdered his 2yr old daughter, convinced his wife n daughter were possesed by the devil after watchin a horror fil "BUG". Does this imply that there are definate triggers, which flip otherwise normal people into lunatic mode???