Right away, he started scrabbling with me, trying to pull free, then trying to bite me. Sampson got there and put a knee down on his back while I stood up.

“Sir, stop moving!” John shouted at him as I started a quick pat down.

“No! No! Please!” he yelled from the ground. “I haven’t done anything! I am an innocent person!”

“What’s this?”

I had pulled a knife out of the side pocket of his filthy barn coat. It was sheathed in a toilet paper roll and wrapped in duct tape.

“You can’t take that!” he said. “Please! It is my property!”

“I’m not taking it,” I told him. “I’m just holding on to it for now.”

We got him up on his feet and walked him back over to the wall to sit down.

“Sir, do you need medical attention?” I asked. There was an abrasion on his forehead from where we went down. I felt a little bad about that. Trembling here in front of me, he just seemed kind of pathetic. Never mind that he’d been holding his own until a minute ago, trying to bite off one of my fingers.

“No,” he said. “No.”

“You’re sure?”

“I am not required to talk to you. You have no reason to arrest me.”

His English was good, if a little stilted. And he obviously wasn’t as out of it as I’d thought, although he still wouldn’t look at us.

“How about this?” I said, indicating the knife. I handed it to Sampson. “Look, you just ran away from your dinner. You want a hot dog? Something to drink?”

“I am not required to talk to you,” he said again.

“Yeah, I got that. Coke okay?”

He nodded at the ground.

“One hot dog, one Coke,” Sampson said, and headed over to the carts on D Street. I could see Siegel and his guys on the sidewalk, waiting to find out what had happened. At least Max was keeping his distance; that was a welcome change.

“Listen,” I said. “You notice I haven’t asked for your name, right? All I want is to find the guy in the picture, and I think you know something you’re not saying.”

“No,” he insisted. “No. No. I am just a poor man.”

“Then why did you run?” I said.

But he wouldn’t answer, and I couldn’t force him. He was right about that. My hunch wasn’t enough to detain him.

Besides, there were other ways to get information.

When Sampson came back with the hot dog, the guy ate it in three bites, downed the soda, and stood up.

“I am free to go, yes?” he said.

“Take my card,” I said. “Just in case you change your mind.”