“And that somebody was Milburgh?” said Whiteside.
Tarling made no reply. He had his own views and for the moment was not prepared to argue.
“It was obviously Milburgh,” said Whiteside. “He comes to you in the night — we know that he is in Hertford. We know, too, that he tried to assassinate you because he thought the girl had betrayed him and you had unearthed his secret. He must have killed his wife, who probably knows much more about the murder than the daughter.”
Tarling looked at his watch.
“Ling Chu should be here by now,” he said.
“Oh, you sent for Ling Chu, did you?” said Whiteside in surprise. “I thought that you’d given up that idea.”
“I ‘phoned again a couple of hours ago,” said Tarling.
“H’m!” said Whiteside. “Do you think that he knows anything about this?”
Tarling shook his head.
“I believe the story he told me. Of course, when I made the report to Scotland Yard I did not expect that you people would be as credulous as I am, but I know the man. He has never lied to me.”
“Murder is a pretty serious business,” said Whiteside. “If a man didn’t lie to save his neck, he wouldn’t lie at all.”
There was the sound of a motor below, and Tarling walked to the window.
“Here is Ling Chu,” he said, and a few minutes later the Chinaman came noiselessly into the room.
Tarling greeted him with a curt nod, and without any preliminary told the story of the crime. He spoke in English — he had not employed Chinese since he discovered that Ling Chu understood English quite as well as he understood Cantonese, and Whiteside was able from time to time to interject a word, or correct some little slip on Tarling’s part. The Chinaman listened without comment and when Tarling had finished he made one of his queer jerky bows and went out of the room.
“Here are the letters,” said Whiteside, after the man had gone.
Two neat piles of letters were arranged on Mrs. Rider’s desk, and Tarling drew up a chair.
“This is the lot?” he said.
“Yes,” said Whiteside. “I’ve been searching the house since eight o’clock and I can find no others. Those on the right are all from Milburgh. You’ll find they’re simply signed with an initial — a characteristic of his — but they bear his town address.”
“You’ve looked through them?” asked Tarling
“Read ’em all,” replied the other. “There’s nothing at all incriminating in any of them. They’re what I would call bread and butter letters, dealing with little investments which Milburgh has made in his wife’s name — or rather, in the name of Mrs. Rider. It’s easy to see from these how deeply the poor woman was involved without her knowing that she was mixing herself up in a great conspiracy.”
Tarling assented. One by one he took the letters from their envelopes, read them and replaced them. He was halfway through the pile when he stopped and carried a letter to the window.
“Listen to this,” he said:
“Forgive the smudge, but I am in an awful hurry, and I have got my fingers inky through the overturning of an ink bottle.”
“Nothing startling in that,” said Whiteside with a smile.
“Nothing at all,” admitted Tarling. “But it happens that our friend has left a very good and useful thumbprint. At least, it looks too big for a fingerprint.”
“Let me see it,” said Whiteside, springing up.
He went to the other’s side and looked over his shoulder at the letter in his hand, and whistled. He turned a glowing face upon Tarling and gripped his chief by the shoulder.
“We’ve got him!” he said exultantly. “We’ve got him as surely as if we had him in the pen!”
“What do you mean?” asked Tarling.
“I’ll swear to that thumbprint,” replied Whiteside. “It’s identical with the blood mark which was left on Miss Rider’s bureau on the night of the murder!”
“Are you sure?”
“Absolutely,” said Whiteside, speaking quickly. “Do you see that whorl? Look at those lineations! They’re the same. I have the original photograph in my pocket somewhere.” He searched his pocketbook and brought out a photograph of a thumbprint considerably enlarged.
“Compare them!” cried Whiteside in triumph. “Line for line, ridge for ridge, and furrow for furrow, it is Milburgh’s thumbprint and Milburgh is my man!”
He took up his coat and slipped it on.
“Where are you going?”
“Back to London,” said Whiteside grimly, “to secure a warrant for the arrest of George Milburgh, the man who killed Thornton Lyne, the man who murdered his wife — the blackest villain at large in the world to-day!”
XXIX. The Theory of Ling Chu
Upon this scene came Ling Chu, imperturbable, expressionless, bringing with him his own atmosphere of mystery.
“Well,” said Tarling, “what have you discovered?” and even Whiteside checked his enthusiasm to listen.
“Two people came up the stairs last night,” said Ling Chu, “also the master.” He looked at Tarling, and the latter nodded. “Your feet are clear,” he said; “also the feet of the smallpiece woman; also the naked feet.”
“The naked feet?” said Tarling, and Ling Chu assented.
“What was the naked foot — man or woman?” asked Whiteside.
“It may have been man or woman,” replied the Chinaman, “but the feet were cut and were bleeding. There is mark of blood on the gravel outside.”
“Nonsense!” said Whiteside sharply.
“Let him go on,” warned Tarling.
“A woman came in and went out—” continued Ling Chu.
“That was Miss Rider,” said Tarling.
“Then a woman and a man came; then the barefooted one came, because the blood is over the first women’s footmarks.”
“How do you know which was the first woman and which was the second?” asked Whiteside, interested in spite of himself.
“The first woman’s foot was wet,” said Ling Chu.
“But there had been no rain,” said the detective in triumph.
“She was standing on the grass,” said Ling Chu, and Tarling nodded his head, remembering that the girl had stood on the grass in the shadow of the bushes, watching his adventure with Milburgh.
“But there is one thing I do not understand master,” said Ling Chu. “There is the mark of another woman’s foot which I cannot find on the stair in the hall. This woman walked all round the house; I think she walked round twice; and then she walked into the garden and through the trees.”
Tarling stared