You could make the same argument for why serial killers shouldn't keep trophies ... but they do. The trophies are said to allow the killer to relive their crim

You could make the same argument for why serial killers shouldn't keep trophies ... but they do. The trophies are said to allow the killer to relive their crime - perhaps the ledger is an effort to validate the paedophile's acumen as a business person? Or maybe he was making enough cash that he needed to accurately launder it through his other businesses?