"I think I do," he replied, abstractedly.
"How was it?" I prompted, for his mind was now on the telegram.
"A poison-gas pistol," he resumed, coming back to the work he had just been doing. "Instead of bullets, this pistol used cartridges charged with some deadly powder. It might have been something like the anesthetic pistol devised by the police authorities in Paris some years ago when the motor bandits were operating."
"But who could have used it?" I asked.
Kennedy did not answer directly. Either he was not quite sure yet or did not feel that the time was ripe to hazard a theory. "In this case," he continued, after a moment's thought, "I shouldn't be surprised if even the wielder of the pistol probably wore a mask, doubly effective, for disguise and to protect the wielder from the fumes that were to overcome the victim."
"You have no idea who it was?" I reiterated.
Before Kennedy could answer there came a violent ring at the laboratory bell, and I hurried to the door. It was one of the bell-boys from the hotel where the Barrioses had their apartment, with a message for Kennedy.
Craig tore it open and read it hurriedly. "From Doctor Scott," he said, briefly, in answer to my anxious query. "Barrios is dead."
Even though I had been prepared for the news by my last visit, death came as a shock, as it always does. I had felt all along that Kennedy had been called in too late to do anything to save Barrios, but I had been hoping against hope. But I knew that it was not too late to catch the criminal who had done the dastardly, heartless deed. A few hours and perhaps all clues might have been covered up. But there is always something that goes wrong with crime, always some point where murder cannot be covered up. I think if people could only be got to realize it, as my experience both on the Star and with Kennedy have impressed it on me, murder would become a lost art.
Without another word Kennedy seized his hat and together we hurried to the hotel.