You can request copies of bank statements, mortgage documents, and other financial information from the deceased person's bank or financial institution. Often, these institutions will require a death certificate or other proof of death before they will release any information.
The beneficiary generally does not need to hire a lawyer or file anything in court to access the funds. They should be able to simply present the bank with proof of the death (e.g. a death certificate) as well as proof of their own identity, and the bank should release the funds directly to them.
If you know the account details and the bank or provider, then contact it in the first instance to track the account down. The process varies from case to case – and will to some extent depend on whether there was a will and if the original estate was administered via a grant of probate.
If you are unsure where the decedent banked, you may consider asking the decedent's family members, the executor/administrator of their estate or the trustee of their trust. You also could try visiting banks in the vicinity of where the decedent had resided to ask them about your beneficiary status in person.
The account holder only needs to notify their bank of who the beneficiary should be. The bank, on its end, will give the account owner a beneficiary designation form to fill out. The completed form gives the bank authorization to convert the account to a POD.