(NewsNation) — A grandmother of four solved her own murder, according to Arizona police.

Pamela Martinez, 60, was working as a food delivery driver when police say a van pulled up alongside her car. Martinez took a picture of the van and a man who approached her just moments before he shot and killed her, according to police.

Police later identified that man in the picture as 62-year-old Rusty French. He now faces one count of second-degree murder.

“She (Martinez) took the final moments of her life and did the only thing she could think of and took a very clear photo,” Officer Tiffany Ngalula said during an appearance Wednesday night on “NewsNation Prime.” “We don’t know what happened prior to that or what led up to it that caused the altercation between them.”

Ngalula said law enforcement used photo recognition to identify French through the Arizona Department of Transportation.

“We initially brought him in, and he told us that ‘Yes,’ he remembered her taking a photograph of him, but all he could say was that he ‘possibly blacked out and doesn’t know what actually happened,'” Ngalula said.

Authorities recovered quite a few guns at French’s residence.

“We’re not really sure what triggered him. I mean, that’s gonna take a lot to shoot a complete stranger,” Ngalula added.