If a matter is referred to GSOC, does An Garda Síochána have no further involvement in its investigation?

Chapter 4 and Appendices A and B of the Protocols between the two
organisations are about investigations that coincide.
Where a referral is made to GSOC by An Garda Síochána, GSOC has a
responsibility to investigate the matter, and this may include investigation
of civilian behaviour as well as garda behaviour.