Disgraced former New England Patriot Aaron Hernandez may have left hidden wealth for his 5-year-old daughter beyond the reach of his creditors in a trust he set up before his prison suicide in April. The “AJH Irrevocable Trust” came to light in documents filed in Bristol Probate and Family Court by attorney John G. Dugan, the special representative of Hernandez’s purportedly destitute estate. A key purpose of irrevocable trusts is to protect beneficiaries from other claims because the creator relinquishes ownership and control of the assets set aside. The contents of the trust are also not public record. Boston law firm Rubin and Rudman, which helped Hernandez set up the trust, was ordered last week by Judge Richard J. McMahon to turn over confidential “documents and related materials” that Dugan told McMahon he needed help to obtain, court records state. McMahon held a closed-door hearing on the matter, slapped a gag order on those present, then took the extra step Friday of impounding a recording of what was discussed.