He was a prominent member of a Noongar art movement that emerged among children living at Carrolup Native Settlement during the late 1940s and early 1950s.
During the late 1940s artwork created by the Carrolup children was exhibited in the Western Australian capital Perth and overseas in India.
After leaving school in 1951 he was briefly engaged as a commercial artist in Perth before moving back to Carrolup to work as a farm worker and railway fettler.
The jury strongly recommended mercy, and the judge told Cooper that alcohol "is the source of your trouble" and sentenced him to four years imprisonment.
While at Fremantle he also painted twelve works depicting the Stations of the Cross (now lost) for the restoration of the Sacred Heart Church in Mount Barker.