You can use many adjectives, it depends on the speaker and the circumstance. For instance, I can say, "That man committed horrible crimes against nature, by allowing the slaughter of innocent baby seals." I do hope this helps you.
Well, I need it for a title. 'Perfect crime' is too widespread. So I was thinking about magnificent crime or excellent crime. The thing is, I 'googled' it and didn't find magnificent/excellent crime combinations. That's why I am wondering if it's correct
Perfect crime suggests that you think the crime was very well planned and executed. Magnificent/excellent suggest that you approve of the crime, ie these adjectives suggests a moral judgement.