There is no trace from a dead body back to the original act of killing, but police regularly manage to link them anyway (at least when the body had a large enough bank account).
They do this by means such as "questioning people" and "finding evidence". For example, if you have a file on your computer describing your plan to use XOR to infringe copyright, that would be considered "evidence".
This steps over the fact that the first crime is considerably messy while the other is extremely clean and can be committed where the law cannot see without a warrant.
They do this by means such as "questioning people" and "finding evidence". For example, if you have a file on your computer describing your plan to use XOR to infringe copyright, that would be considered "evidence".