Born in Murray Bridge, South Australia, Overland was raised in Canberra and attended Holder High School and Stirling College before gaining qualifications from the University of Canberra (Bachelor of Arts in Administration and a Graduate Diploma in Legal Studies) and the Australian National University (Bachelor of Laws, first class honours).

He served about 19 years with the AFP; during this time he was selected by Australia's police commissioners to lead the Implementation Team that created the Australian Crime Commission in January 2003.

In 2011 there was an Ombudsman investigation into allegations that Overland willingly aided in selectively releasing crime statistics to help make the former Labor-based Brumby government appear more favourable to voters when law and order was considered a major political issue.

[10] The Ombudsman, George Brouwer, investigated the interaction between the former government and senior police figures ahead of the release of the crime statistics on 28 October 2010.

[10] Even before the Ombudsman's report was completed, it was expected to be critical of the relationship between the Brumby government and police force.

After initially taking indefinite leave in November 2019[14] he was removed from this position following a Whittlesea City Council meeting on 10 December 2019, a week before his scheduled appearance at the Royal Commission into the Management of Police Informants.