Black Hood turned the ultra-violet lamp on the desk. The box of powder there became phosphorescent.
"When I was framed for the Tauber jewel robbery tonight, I seized the opportunity to toss some of this face powder onto the jewels in the robbers' bag," Black Hood continued. "The face powder is that of Vida Gervais. Watch, please."
Black Hood turned the ultra-violet lamp out toward his audience. Vida Gervais' frightened face glowed in the black light. Startled gasps could be heard from the others in the room as they stared at that ghostly face.
"Vida Gervais," Black Hood continued, "knew a good thing when she saw it. To eventually better her social and financial position, she was willing to sell out Carlson, alias the Eye, to another man who, if he could accumulate, through fair means or foul, quite a tidy sum of money now would get his hands on a great deal more money in the future.
"So Vida Gervais betrayed Carlson, alias the Eye, into the hands of the man who had killed Biggert. The forty thousand dollars which this man had got from the forged check was a small part of the money he needed. But if he could step into the Eye's shoes for a little while, he could rapidly accumulate the rest.
"I mentioned a moment ago that I had tossed some of Vida Gervais' unusual face powder onto the diamonds stolen from Tauber's shop. The naphthionate in that powder would cling to the diamonds and subsequently cling to the hands of the criminal who eventually got hold of them. Watch now for the glowing hands of the killer—the man who has been impersonating the Eye ever since Carlson was killed. But one funny thing about that impersonation which I did not realize until tonight. The impersonator, this man who killed Biggert and Carlson, was most careful to avoid any word or name beginning with the letter 'D.' He would not, for instance, say the name 'Delancy,' nor would he speak the word 'diamonds.' Why? Because every time he says a word or name beginning with that letter, he stutters. He might disguise his voice by whispering, but he could not control this stutter, which would have been a dead give-away."
In the black light, luminous fingers suddenly showed themselves. There was a piercing scream. Men surged forward to close in and blot out the glow from the killer's fingers.
"Watch out!" Black Hood's warning voice rang out. "He is probably armed!"
Men bumped into each other. There was the repeated thud of blows. There were cries, grunts, stammered oaths. And when finally somebody turned on the lights, Jeff Weedham was on the floor, two cops astride him. He had a gun in his hand, but his hand was pinned to the floor.