ANTHEM, AZ - Arizona weapons experts believe one person used the same assault rifle to gun down a sheriff's deputy in Phoenix and a New Hampshire couple near the scenic resort town of Sedona, authorities said Tuesday.
Maricopa County Sheriff's Deputy William Coleman was gunned down Sunday at a north Phoenix medical building while answering a burglary call.
On Friday, James Johnson of Jaffrey, N.H., and Carol Raynsford of Nelson, N.H., were found dead in a sedan at a remote highway turnout near Sedona.
"It was a quick death for the victims," Yavapai County Sheriff Scott Mascher told reporters.
The deaths of the New Hampshire friends have baffled authorities and led to speculation that the killings were committed by Drew Ryan Maras , who died in Sunday's shootout with officers in Phoenix.
"I don't think we will ever know the motive," added Mascher.
The same gun -- an AR-15 variant -- was believed to have been used in both cases, and the crime scenes are connected by Interstate 17, authorities said.
The Maricopa County Sheriff's Office announced the link in a statement handed out to reporters before a Tuesday morning news conference.
Maras had lost his maintenance job, was living out of a van and was likely suffering from depression, authorities said. He fired 29 shots at deputies on Sunday before he was killed.
"We returned the fire 41 times," said Maricopa County Sheriff Joe Arpaio. "Some say that's overkill. That's the way it goes. Maybe we ran out of bullets too early."
In the shooting near Sedona, detectives found numerous casings from a .223-caliber rifle on both sides of Johnson and Raynsford's car. Some callers reported seeing the car parked at the turnout on Thursday.
Johnson and Raynsford, both 62, were looking for a house for Johnson and planned to head home at the end of the month, said Raynsford's piano teacher and friend, Jayne Kelly. The pair belonged to a nonprofit group that adopts and preserves parts of a 48-mile hiking trail from Mount Monadnock in New Hampshire.
"It's very sad and senseless and horrific," said Mascher.
Coleman, 50, was a 20-year veteran. He is survived by a wife and two young children, ages 4 and 7. He also has grown children in another state. He was assigned as a patrol deputy but had previously worked the sheriff's lake patrol unit.
Maras, 30, attended Arizona State University in 2004 but wasn't currently enrolled, university spokeswoman Julie Newberg said.
Before that, he served with the U.S. Marine Corps from 1999 to 2003, completing infantry training with a specialty as a rifleman before joining a reserve unit in Chicago, Marine Maj. Shawn Haney said.