Did he leave an IRA too? Chances are he took the PS money and rolled it over. Unless he had other employment that explains the IRA existence, you may want to assume that's the Lever money.
Years ago, a relative died and we ran across a life insurance policy. Luckily, the insurer was still in business and was able to confirm that the policy had long ago been cashed out. Do your heirs a favor and leave a paper trail with notes about which policies and assets are still valid. Write a note on account statements when you close them down.
Better yet, have a conversation and make a list of active accounts. Don't leave it to guesswork!