Previously working as a commercial solicitor, Lethlean began working for the AFL in 2004. He worked across various roles at the league, where he was involved in the legal department, broadcasting, fixturing, and game development. As general manager of game development at the league he was involved in the creation of the
AFL Women's league, and oversaw its inaugural season. In March 2017, AFL CEO
Gillon McLachlan announced that Lethlean would be replacing outgoing football operations manager Mark Evans, who was taking on the CEO position at
Gold Coast Football Club. It emerged that Lethlean had been involved in an extra-marital relationship with a younger female staff member from the AFL's New South Wales office. The relationship had begun a year earlier in August 2016, but had ended prior to Lethlean taking on the football operations role. He also resigned from his position as a director of statistics company
Champion Data, which is part owned by the league. Following his departure from the AFL, it was reported that Lethlean was seeking a CEO position at an AFL club. He had been linked to chief executive openings at
Collingwood,
Carlton, and
Hawthorn, and later to the head of football department role at
Essendon, but in December 2017 it was announced that he would become general manager of football at the St Kilda Football Club from the beginning of 2018. The role became vacant following a restructure caused by the departure of Saints chief operating officer Ameet Bains. == Playing/coaching career ==