If the decedent had a Will, then the person with custody is required to deposit the Will with the probate court in the county where the decedent was a resident at death. So, you can check with the probate court.

Although not required, the creator of a trust (aka "settlor" or "trustor") can record a "declaration of trust" with the county clerk, to evidence the existence of a trust. So, you can also check the county clerk for a record of the trust.

If neither of the above works, then you would have to file an action in probate court, allege that the trust existed, that you lost the paperwork, and that you seek a judgment of the trust assets belong to you. Then, you could use the court's subpoena powers to start subpoenaing banks and investment companies, until one of them produces an account that identifies the trust. Meanwhile, if there are any surviving relatives, and/or the decedent has any personal property subject to probate, you could subpoena each person and simultaneously seek an order permitting you to inspect the decedent's personal effects -- or you could petition to be named personal representative and then you could collect all of your friend's assets yourself, and probably find the trust account and trust instrument among your friend's effects.

All of this would be a costly investigation and legal action, but if this irrevocable trust is valuable, then maybe it's worth the effort.

You'll never do it without hiring a lawyer, in my opinion. So, for a competent estate litigation attorney referral, see this link.

Note: One other, and possibly less costly approach would be to contact the surviving relatives and friends and simply tell them that if they can help you find the trust instrument and account that you will give them a piece of the pie. This may seem like an even more expensive option, but it's probably not. I could see this sort of investigation easily running in excess of $25,000, if you use a lawyer and the court system.

Hope this helps.

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