He served as Commissioner of the Northern Territory Police Force from November 2019 to April 2023, when he resigned under pressure, seven months before his contract was due to expire.
He began his career in the Northern Territory Police Force in 1994, where he remained served in various roles, much of the time in remote localities.
This was around the time Police Commissioner John McRoberts was charged with, and later convicted of, attempting to pervert the course of justice in a travel agent investigation.
Chalker asked the court to be given an opportunity to respond to Fyles' allegations before any steps were taken to revoke his appointment as police commissioner.
[5] In 1999, Commissioner Chalker was awarded a Royal Humane Society Bronze Medal for Bravery for entering flood waters and rescuing a man who had been swept down-river in Wattie Creek, near Daguragu, Northern Territory.