Questions have been raised over Racing Victoria’s handling and investigation of a recent doping scandal that resulted in three people being banned for life and five others penalised.

The ABC Four Corners program was told that investigations into banned trainer Robert Smerdon should have started earlier given his previous transgressions and unusually long winning streak.

A transcript of the initial investigation obtained by the program shows that when the scandal broke racing stewards did not forensically examining Smerdon’s phone and allowed him to take it with him when he left the racecourse.

Racing Victoria’s chief executive Giles Thompson told Four Corners it was a choice he was comfortable with.