Recruiting assistant Paul Brodie has resigned from GWS after the AFL's move to ban him for a betting offence.
Brodie was caught placing a $100 head-to-head multi bet on five matches in round 19, including one involving the Giants.
The league detected the successful bet, where Brodie won $945.
The AFL banned him on Thursday for 13 months until December 1 next year, prompting Brodie to quit the Giants.
Players, coaches and officials cannot bet on AFL matches.
AFL general counsel Andrew Dillon said the bet was detected by their integrity department.
"I have made a mistake which has let the club down, let down my family and friends, and let myself down," Brodie said in a GWS statement.
"I am very sorry for the lack of respect I have shown for the rules and principles that maintain the integrity of our game.
"I will accept whatever sanction is imposed on me as an appropriate penalty.
"I have learned a serious lesson and hope others can also learn from my mistake."