Does the perfect crime exist, only I suspect in the vivid imaginations of crime fiction writers.
The nearest thing I have come across as potentially the perfect crime was in the 1983 Superman III film when Gus Gorman played by Richard Pryor wrote a small piece of software to collect all the fractions of a cent left over after rounding down employees pay and expenses and had them all paid into his account. The problem was he was paid such a large amount of money that it drew his boss’ attention to him and then it started to go horribly wrong.
In theory this ought to work, it doesn’t physically harm anyone, the company was rounding down the figures because you cannot pay parts of a cent and by adding them all together you reach a respectable sum. Providing you also write in a sensible upper cut off limit per month I see no reason why this shouldn’t go undetected for years. In my opinion a near perfect crime, but could you live with the guilt?