building—grocery downstairs, grocer’s flat upstairs. Behind these buildings runs a narrow back street—an alley. All right.
“Kinney—the patrolman on that beat—was walking down Eighteenth Avenue. He heard the shot. It was clear to him, because the Mains’ apartment is on that side of the building—the side overlooking the grocer’s—but Kinney couldn’t place it right away. He wasted time scouting around up the street. By the time he got down as far as the alley in his hunting, the birds had flown. Kinney found signs of ’em though—they had dropped a gun in the alley—the gun they’d taken from Main and shot him with. But Kinney didn’t see ’em—didn’t see anybody who might have been them.
“Now, from a hall window of the apartment house’s third floor to the roof of the grocer’s building is easy going. Anybody but a cripple could make it—in or out—and the window’s never locked. From the grocer’s roof to the back street is almost as easy. There’s a cast iron pipe, a deep window, a door with heavy hinges sticking out—a regular ladder up and down that back wall. Begg and I did it without working up a sweat. The pair could have gone in that way. We know they left that way. On the grocer’s roof we found Main’s wallet—empty, of course—and a handkerchief. The wallet had metal corners. The handkerchief had caught on one of ’em, and went with it when the crooks tossed it away.”
“Main’s handkerchief?”
“A woman’s—with an E in one corner.”
“ Mrs. Main’s?”
“Her name is Agnes,” Hacken said. “We showed her the wallet, the gun, and the handkerchief. She identified the first two as her husband’s, but the handkerchief was a new one on her. However, she could give us the name of the perfume on it— Dèsir du Cœur . And—with it for a