Tucker was originally an officer in the New Zealand Army, holding the rank of Major. He has a doctorate in electrical engineering from the University of Canterbury, and later joined the Government Communications Security Bureau (GCSB), New Zealand's primary signals intelligence agency. He became head of communications security in 1982, and in 1983, he was appointed Director of Policy and Plans. From 1984 to 1989, he was the GCSB's liaison officer to the NSA in Washington. On his return, he became Director of Operations (effectively deputy director of the GCSB), and in 1996, he became the Intelligence Co-ordinator in the office of the Prime Minister. He became the third director of the GCSB in 1999, replacing Ray Parker. In 2006, it was announced that he would succeed Richard Woods as director of another New Zealand intelligence agency, the Security Intelligence Service, on 1 November.