In the interest of preserving its integrity, the Arizona Department of Public Safety has refused to discuss details of the investigation into the I-10 shootings.

But the science of gunshots is playing a large role.

Ballistics expert Mike Haag said investigators are likely poring over holes, trajectories and casings.

“Trying to establish as best as possible where the vehicle was when it was struck, and then we can, in fact, extrapolate the trajectory to potential areas where the shots came from. I think that’s what on everybody’s mind, first,” Haag said.

Haag and his father, Luke, who are each from Phoenix, are co-authors of the book “Shooting Incident Reconstruction,” which is used to train law enforcement.