When you are dealing with an application under section 153, Public Trust must choose a person, called the investigator, in a specific way. The investigator must be either a lawyer or a qualified statutory accountant, which means they must meet the requirements set out in section 5(1) of the Financial Reporting Act 2013. The investigator cannot be a beneficiary of the trust.

The investigator can be chosen in two ways: by agreement between certain people, including Public Trust, or by Public Trust if no agreement can be reached. If an agreement is reached, it must be between the applicant trustee, the co-trustees, and Public Trust, or between the applicant beneficiary, the trustees, and Public Trust. Public Trust will choose the investigator if the required people cannot agree on who it should be.