If you buy a gun at a gun store (assume its done legally with a background check and waiting period) and then you kill someone, is the gun store owner responsible? No.
A bartender serves you one or two drinks, you get drunk and kill someone with your car, is he/she responsible? No.
You buy spray paint at home depot and vandalize a car, is home depot responsible? No.
You download hi res images from a website and create fake posters, is the website responsible? No.