Much depends on the local laws relating to confiscations of criminal profits. Some follow a model which requires a conviction before the confiscation laws are engaged, some do not. One can argue about the principles underlying this, but that is of marginal interest for present purposes.
However, the confiscation laws generally are only relevant in triggering the capacity of the state to get hold of the loot. For offences like drug dealing, etc, only the state has an interest in pursuing the money, because there is usually no “victim” who has an enforceable interest in clawing back drug profits.
Fraud cases are a different matter. If you defraud me, I can sue you, and the success or otherwise of my suit does not depend on the existence of a conviction (the principle was engaged in the case of the suit against OJ even after he was acquitted). If you, the fraudster, die for some reason before my suit is complete, then your estate remains liable to pay, and that liability takes precedence over any will. The usual rule is that what is distributed after death to rellies, etc, is what is left after all debts are paid, and my suit against you will create a debt (if I win).
Generally, if you are a banker who steals money from various accounts, a whole raft of potential plaintiffs might be able to sue, but generally, the bank will pay out the small fry whose accounts were emptied, then use its clout to finance going after the yacht, the Ferrari, the beach house, etc.
If you are not a banker, but just some spiv in the finance world who rips off clients, then there is a fair chance that you will have made some attempt to stash the money in accounts in false names, etc, which might make it harder to retrieve, but with the death of the fraudster, there is less capacity for him to try to obscure the retrieval of such money with bullshit. If I have lost enough money, and the chances seem worthwhile that I can get hold of enough of your assets to make it worth my while to sue, then I will make a commercial decision about whether to strip your grieving widow of said yacht, etc.