The Michigan State Police said in a press conference Tuesday morning that Trooper Paul Butterfield (pictured) of the Hart Post followed protocol in a traffic stop, and that helped authorities catch the suspects in his shooting death.

At 6:20 Monday evening, he made a traffic stop on Custer Rd. near Townline Rd. in Mason County.  At 6:23, a passerby found Tpr. Butterfield on the ground with a gunshot wound to the head and called 911.

Tpr. Butterfield died in surgery at Munson Hospital in Traverse City.

Col. Kriste Kibbey Etue, director of the MSP, said in a statement "we lost a hero.  The entire MSP family, as well as our greater law enforcement family, mourns alongside the Butterfields.  Trooper Butterfield's sacrifice will never be forgotten; may he rest in peace."

Authorities identified a suspect based on the license plate and vehicle description Tpr. Butterfield shared as he made the traffic stop, and they found the suspect with another individual at a Manistee County convenience store about two hours after the shooting.  There, the suspects exchanged gunfire with law enforcement agents and one suspect was shot.

The suspects, a male and a female, were arrested.  WOOD TV reports the male suspect's grandmother identified them as Eric and Sarah Knysz.