A half-hour later detective headquarters at the Central Station received an anonymous tip:  “Send some one to the office of the International Machine Company, on the second floor of West Superior Street.”

It was ten thirty when Jimmy reached the plant.  He entered the front door with his own latchkey, pressed the button which lighted the stairway and the landing above, and, ascending, went straight to Mr. Compton’s office, turned the knob, and opened the door, to find that the interior was dark.

 “Strange,” he thought, “that after sending for me the fellow didn’t
 wait.”  As these thoughts passed through his mind he fumbled on the wall
 for the switch, and, finding it, flooded the office with light.

As he turned again toward the room he voiced a sudden exclamation of horror, for on the floor beside his desk lay the body of Mason Compton!  As Jimmy stepped quickly toward Compton’s body and kneeled beside it a man tiptoed quietly up the front stairway, while another, having ascended from the rear, was crossing the outer office with equal stealth.

Jimmy felt of Compton’s face and hands.  They were warm.  And then he placed his ear close against the man’s breast, in order to see if he could detect the beating of the heart.  He was in this position when he was startled by a gruff voice behind him.

“Put ’em up!” it admonished curtly, and Jimmy turned to see two men standing in the doorway with pistols leveled at him.

CHAPTER XXV.

Circumstantial evidence.

At first Jimmy thought they were the perpetrators of the deed, but almost immediately he recognized one of them as O’Donnell, the erstwhile traffic officer who had been promoted to a detective sergeancy since Jimmy had first met him.

“Compton has been murdered,” said Jimmy dully.  “He is dead.”

“Put up your hands,” snapped O’Donnell for the second time, “and be quick about it!”

It was then for the first time that Jimmy realized the meaning that might be put upon his presence alone in the office with his dead employer.  O’Donnell’s partner searched him, but found no weapon upon him.

“Where’s the gat?” he asked.

“Whoever did this probably took it with him,” said Jimmy.  “Find the watchman.”

They made Jimmy sit down in a corner, and while one of them guarded him the other called up central, made his report, and asked for an ambulance and the wagon.  Then O’Donnell commenced to examine the room.  A moment later he found an automatic behind the door across the room from where Compton’s body lay.

“Ever see this before?” asked O’Donnell, holding the pistol up to Jimmy.

“If you’re asking me if it’s mine, no,” said Jimmy.  “I have a gun, but it’s home.  I never carry it.  I didn’t do this, O’Donnell,” he continued.  “There was no reason why I should do it, so instead of wasting your time on me while the murderer escapes you’d better get busy on some other theory, too.  It won’t do any harm, anyway.”