The Branch was formed on 1 November 1919 by an amalgamation of the Special Intelligence Bureau (CA 746) and the almost defunct
Commonwealth Police Force [I] (CA 2919). Major H E Jones was gazetted Director from that date and Inspectors in charge of the various State Branches were appointed. (Commonwealth Gazette, No.72, 2 September 1920, p.1156).

In 1919, records relating to the war, 1914-1918, were transferred to the Branch by the Director of Military Intelligence and the Censor. The Branch was located in Melbourne until 1927, and when it moved to Canberra a State office was set up in Victoria (CA 907).

It appears that the Peace Officer Guard, set up under the Peace Officers Act 1925, and responsible to the Attorney-General, came under the control of the Investigation Branch (circa 1927).
The Director of the Investigation Branch was made Chief Officer of the Federal Capital Territory Police under the Police Force Ordinance 1927 (Territory for the Seat of Government Ordinance No.19/1927 Section 5(3) in Commonwealth Gazette, No.101, 27 September 1927, p.1986) and would appear to have held that position until cira 1943, when records were passed to the Australian Capital Territory Police (CA 665).

In 1941, the Security Service (CA 660) was established to deal with war-time security. On its abolition in 1946, some of its records were passed to the Investigation Branch.

On 8 August 1946 the reorganisation of the Branch was notified in the Gazette and its positions abolished and recreated (Commonwealth Gazette, No. 145, 8 August 1946, p.2149-2150). Inspectors in charge of the State branches were replaced by Deputy Directors; the central staff and each branch was divided into two sections, the Investigation Section and the Security Section. The Federal Guide 1947 shows a name change to Commonwealth Investigation Service (CA 650), a change which is not reflected in the Commonwealth Gazette until 1955. The date of the change of name from Investigation Branch to Commonwealth Investigation Service is not known but has been presumed to be 8 August 1946.
 

Historical agency address
by1921-by1927: Queen's House, 140 Queen Street, Melbourne Vic
by1936-by1943: East Block, Canberra ACT
by1943-by1946: Patent Office Building, Barton ACT