Drafftiwyd Protocol Gweithredol gan yr Ysgrifennydd Parhaol a'i thîm cyfreithiol a oedd yn diwallu'r cylch gwaith yn llawn. Roedd hefyd yn cynnwys mesurau diogelu sylweddol i sicrhau cyfrinachedd y tystion a'r wybodaeth sy'n gysylltiedig â'r Ymchwiliad. Rhoddwyd rhestr fer o dri Chwnsler y Frenhines uchel eu parch o'r tu allan i Gymru i’r teulu Sargeant a gofynnwyd i'w dewis cyntaf, Paul Bowen CF, gynnal yr ymchwiliad ar sail y Protocol Gweithredol fel y'i drafftiwyd. Dywedodd Mr Bowen CF nad oedd dim yn ei rwystro rhag ymgymryd â'r rôl, yn seiliedig ar y Protocol Gweithredol.
The Permanent Secretary and her legal team drafted an Operational Protocol which met the remit in full, and contained substantial safeguards for the confidentiality of witnesses and information related to the Investigation. A shortlist of three highly respected QCs based outside Wales was provided to the Sargeant family and their first choice, Paul Bowen QC, was approached to undertake the investigation on the basis of the Operational Protocol as drafted. Mr Bowen QC indicated there was no impediment to him taking up the role, based on the Operational Protocol.