POTRERO CENTER WAS ON Sixteenth and Bryant, a modern strip mall of wall-to-wall retail stores: Office Depot, Safeway, Jamba Juice, and more. A stone wall with a metal rail on top enclosed the vast parking lot that was nearly always packed.

The sun was going down when we drove between the stone pillars on Sixteenth and identified ourselves to the uniformed cops at the entrance. I asked for the name of the first officer, then Conklin parked our car near the dozen or so squad cars right inside the gates.

We headed toward the yellow tape at the perimeter, and as we worked our way through the shifting crowd, I saw fear and anger on the faces of shoppers. Clearly, they’d been told that no one could leave the lot without giving a statement, and the handful of officers on the scene were just starting a process that could go long into the night.

The first officer was Mike Degano, a young guy who had been a block away when the call came over his radio. He wanted to help, had the look of a patrolman who aspired to work homicide.

Degano pointed to a late-model black Mercedes XL, said to us, “That’s probably the DB’s car. He had a Mercedes key ring in his hand when he went down. Car is registered to Raoul Fernandez. I ran his name. He has a record for assault and for possession with intent. Spent a couple of years at Folsom, released in 2010. Wait’ll you see this.”

Conklin and I walked with Degano to where the body of a heavily tattooed twenty-something man was splayed on the asphalt. His arms were flung out like wings, his legs were twisted. It looked to me as if he’d been walking toward the shopping center, had turned toward his killer, and had been blown off his feet by the four bullets he’d taken to his face.

It took a steady hand and an automatic gun to throw four shots in such a tight pattern. I’m a good shot, and I couldn’t have done it.

I took another look around the lot as lights came on. Shopping carts were adrift, like dinghies on a blacktop sea. Broken paper bags spilled groceries where they’d fallen. I saw surveillance cameras on light poles, but the shooting had taken place a good hundred yards from the closest camera.

“Were there any witnesses?” I asked Degano.

“Yes, ma’am, we have one sort of witness. Mr. Jonathan Nathan, over there. Old white dude. Red shirt. He heard the shots.”

Chapter 56

Chapter 56

JONATHAN NATHAN WAS IN his seventies, stooped, glasses balanced on the lower slope of his nose, red-and-white aloha shirt under a windbreaker, khaki pants. Flip-flops. His eyes switched between us and the parking lot, as though anything could happen, as though he didn’t feel safe.

I said, “Can you tell us what you know?”