"Get a microscope," the chief ordered, "and keep quiet about what is going on in here."
The sergeant nodded and went out.
"What did you say about that smear on the arm of the chair?" asked the chief, then.
He was beginning to understand that there was something besides mental trouble at the bottom of Ned's inquiries.
"I think," was the reply, "that an inspection of the spot will reveal a rubber composition used principally by the thieves of Paris as a paint to prevent palm and finger lines and whorls showing on things they take hold of."
The chief looked at the spot critically.
"Also, shreds from a blue uniform," Ned continued.
"We shall see," replied the chief.
The microscope was soon brought in, and then a close examination of the spot on the arm of the chair was made by the chief.
"What do you find?" asked Ned.