He says the move sets a dangerous precedent for future cases.
Petrin is charged with first-degree murder in the 2012 death of Lorry Ann Santos, a mother who was shot and killed inside her home.
Police say she was gunned down by members of an Alberta gang called the White Boy Posse who targeted the wrong house.
The Saskatoon Police Service and Saskatchewan’s Ministry of Justice say they won’t comment on Pfefferle’s allegation until the trial is over. Closing arguments in the case are to be heard on Wednesday.