Was going through some letters and here is what I found from 2009 boe letters. This is for australia. Just sharing the lines:
'Letters of introduction: Generally speaking, when each elder has had opportunity to read the letter, there would be no need for it to be retained..........
Additionally, any letter of introduction that refers to matters of child abuse should be retained in the confidential file for as long as the accused person remains in the congregation. Should this person move, a new letter should be prepared and sent to the elders in the new congregation outlining the individual's background, current restrictions that apply, what the elders have been doing to protect minors and to assist him, and their present experience with him. In all such cases, a copy of the letter of introduction must be sent to the branch office in a special blue envelope. Any previous letter of introduction held in the congregation's file can then be destroyed.PS to secretary: This letter should be retained in the "AUSTRALIA BRANCH" section of the
congregation's permanent file of policy letters'.
Zing