Marcus was a Senior Analyst focusing on Defence economics and military capability, leaving ASPI in 2023.

Previously he was a senior public servant in the Department of Defence, responsible for ensuring that the government was provided with the best possible advice and recommendations on major capital investments such as the Joint Strike Fighter, Future Frigate and Future Submarine. He also developed and administered Defence’s capital investment program.

Marcus has also worked in Australia’s intelligence community as a terrorism analyst.

Before joining the public service, Marcus had a career as an academic historian in the United States.