with the police. There were a number of types of incidents that the police, or other agencies the IPCC oversees complaints for, must mandatorily refer to the commission. These included deaths in police custody, shootings and fatal traffic incidents as well as allegations that an officer or member of police staff committed a serious criminal offence. Forces could also refer matters voluntarily to the IPCC and the commission could 'call in' any matter where there might have been serious public concern. Once a matter was referred, the IPCC would make a 'mode of investigation' decision to determine how it should be dealt with. This was done by caseworkers or investigators who submitted an assessment to a Commissioner. The assessment involved judging the available information and could mean IPCC investigators are sent to the scene. The four modes of investigation were: Independent investigations carried out by the IPCC's own investigators and overseen by an IPCC Commissioner. In an independent investigation, the IPCC investigators had all the powers of the police themselves. Managed investigations carried out by police Professional Standards Departments (PSDs), under the direction and control of the IPCC. Supervised investigations carried out by police PSDs, under their own direction and control. The IPCC would set the terms of reference for a supervised investigation and receive the investigation report when it is complete. Complainants had a right of appeal to the IPCC following a supervised investigation. Local investigations carried out entirely by police PSDs, or by other officers on their behalf. Complainants had a right of appeal to the IPCC following a local investigation. Should new information emerge after a mode of investigation has been decided the IPCC could change the classification both up and down the scale. IPCC Investigators were not police officers. However, IPCC investigators designated to undertake an investigation had all the powers and privileges of a police constable in relation to that investigation throughout England and Wales (Police Reform Act, 2002– Schedule 3, Paragraph 19). However, despite being established in April 2004, the first known use of these arrest powers was in 2007 when a former police officer was arrested in relation to allegations of sexual assault. Structure The IPCC was overseen by a chair, two deputy chairs, seven operational and three non-operational commissioners. The chair is a Crown appointment and commissioners were public appointments. The IPCC's commissioners and staff were based in IPCC regional offices in