Dr Keller started working for the Blood Service in 1984 as Director of the WA Division of the then Australian Red Cross Blood Transfusion Service, and was involved in instituting major changes to the donation process, including introduction of the donor questionnaire and donor interview. 

With the formation of the Australian Red Cross Blood Service as a national organisation in 1996, Dr Keller was in charge of both the Western Australian and Northern Territory Blood Transfusion Services. 

Dr Keller was appointed Chair of the National Donor and Product Safety (DAPS) Committee and was primarily responsible for the introduction of many changes to increase donor and product safety within the organisation, including the introduction of nucleic acid testing and a travel deferral to reduce the potential for transfusion transmission of variant Creutzfeldt-Jakob disease.

Dr Keller moved into the full-time role of National Donor and Product Safety Manager in 2003.  Continuing his role as Chair of the DAPS Committee (now the DAPS Advisory Committee), he has played a major role in standardisation of processes across Australia, including bacterial contamination screening, implementation of nucleic acid testing  and universal leucodepletion of red cells and platelets.

In addition to his role at the Australian Red Cross Blood Service, Dr Keller is a member of the Alliance of Blood Operators' Medical Subgroup and the International Blood Emergency Planning Action Group, as well as providing expert advice to the Council of Europe's Committee of Experts on Quality Assurance in Blood Transfusion Services.

Dr Keller has published numerous articles in peer reviewed journals on infectious diseases and the safety of the blood supply, as well as making several presentations to national and international conferences on blood transfusion safety.