It's Tom So He Probably Has A Dedicated File On It - Tumblr Posts

How exactly does Tom know this?

" Hagen said, “What about Luca? Sollozzo didn’t seem worried about Luca. That worries me. If Luca sold us out, we’re in real trouble. That’s the first thing we have to know. Has anybody been able to get in touch with him?” “No,” Sonny said. “I’ve been calling him all night. Maybe he’s shacked up." “No,” Hagen said. “He never sleeps over with a broad. He always goes home when he’s through."

From The Godfather Novel by Mario Puzo.