Authorities are investigating whether a doctor who fatally shot a former colleague outside his New Jersey home was involved in the shooting death in recent days of his girlfriend in North Carolina.

Dr. Giocondo Navek ambushed Dr. Payman Houshmandpour in Voorhees, N.J., as he was leaving for work Wednesday. Minutes later, Navek killed himself when police stopped his vehicle.

Authorities now say the body of Navek's girlfriend, 35-year-old Shawna Dianne Givens, was found at the same day in her apartment in Fayetteville, where she worked as a military nurse and Navek as a military doctor. She is believed to have been killed days earlier.

Tests will determine if the gun that killed Houshmandpour also killed Navek's girlfriend.

Navek had blamed Houshmandpour for his dismissal from a medical residency program.

Get the latest from NBC 4 New York anytime, anywhere. Follow us on Twitter, Facebook and Google+. Sign up for email newsletters here. Get breaking news delivered right to your phone -- just text NYBREAKING to 639710. For more info, text HELP. To end, text STOP. Message and data rates may apply.