Of course, van Heerden had stood because under his foot he had crushed the digitalis tablet he had taken from the phial, and for which he had substituted something more deadly. Had he moved, the powdered tablet would have been seen. It was simple—horribly simple.
He walked slowly back to where he had left Oliva.
What followed seemed ever after like a bad dream to the girl. She was stunned by the tragedy which had happened under her eyes and could offer no evidence which in any way assisted the police in their subsequent investigation, the sum of which was ably set forth in the columns of the Post Record.
"The tragedy which occurred in the Palm-Court of the Grand Alliance Hotel yesterday must be added to the already long list of London's unravelled mysteries. The deceased, a man named Jackson, has been staying at the hotel for a week and was on the point of departure for Canada. At the last moment Dr. van Heerden, who was assisting the unfortunate man, discovered that Jackson was no other than the wanted man in the Millinborn murder, a crime which most of our readers will recall.
"Dr. van Heerden stated to our representative that the man had represented that he was a friend of the late John Millinborn, but was anxious to get to Canada. He had produced excellent credentials, and Dr. van Heerden, in a spirit of generosity, offered to assist him. At the eleventh hour, however, he was struck with the likeness the man bore to the published description of the missing man in the Millinborn case, and was on the point of telegraphing to the authorities at Liverpool, when he discovered that Jackson had missed the train.
"The present tragedy points to suicide. The man, it will be remembered, collapsed, and Dr. van Heerden rendered first aid, administering to the man a perfectly harmless drug. The post-mortem examination reveals the presence in the body of a considerable quantity of cyanide of potassium, and the police theory is that this was self-administered before the collapse. In the man's pocket was discovered a number of cyanide tablets.
"'I am satisfied,' said Dr. van Heerden, 'that the man already contemplated the deed, and when I voiced my suspicions in the palm-court he decided upon the action. The presence in his pocket of cyanide—one of the deadliest and quickest of poisons—suggests that he had the project in his mind. I did not see his action or, of course, I should have stopped him!'"
Oliva Cresswell read this account in her room two nights following the tragedy and was struck by certain curious inaccuracies, if all that the doctor had told her was true.
Mr. Beale read the account, smiled across the table grimly to the bearded superintendent of the Criminal Investigation Department.
"How does that strike you for ingenuity?" he said, pushing the paper over the table.
"I have read it," said the other laconically, "I think we have sufficient evidence to arrest van Heerden. The tile from the Grand Alliance shows traces of digitalis."
Beale shook his head.
"The case would fall," he said. "What evidence have you? We did not confiscate his medicine-case. He might have dropped a tablet of digitalis by accident. The only evidence you could convict van Heerden on is proof that he brought with him cyanide tablets which he slipped into Prédeaux's pocket. No, we can prove nothing."