TMZ reports that the director may have given the former model the gun that was used to shoot Dorian's husband in the back during a domestic dispute in October.
Officials believe that Polanski could have given the weapon to Dorian over 40 years ago, in the wake of the infamous murder of his then-wife Sharon Tate by a group of people connected to Charles Manson.
Sources close to the case have reportedly said that Dorian spent the night prior to Tate's death with the director's wife, and that Polanski handed over the Walther PPK .380 for protection following the attacks.
Investigators now believe that it may have been the weapon used during a fight between Dorian and her husband.
The former model faces life imprisonment if convicted.