An OPP Collision investigator will be allowed to testify at the drunk driving trial of pembroke dentist Christy Natsis. 

Her defense team has been trying to prevent Const. Shawn Kelly from testifying  - arguing he is biased.  Justice Neil Kozloff said today he will rule later whether the testimony will be admissible. 

Natsis is accused of impaired driving causing the death of Bryan Casey in March 2011.