“In some way,” pursued Kennedy in an even voice, “this letter was either overlooked in the original correspondence of Dr. Dixon or it was added to it later.  I shall come back to that presently.  My next point is that Dr. Dixon says he received a letter from Thurston on the day the artist visited the Boncour bungalow.  It asked about a certain headache compound, and his reply was brief and, as nearly as I can find out, read, ’This compound will not cure your headache except at the expense of reducing heart action dangerously.’

“Next comes the tragedy.  On the evening of the day that Thurston left, after presumably telling Miss Lytton about what Kerr & Kimmel had discovered, Miss Lytton is found dying with a bottle containing cyanide and sublimate beside her.  You are all familiar with the circumstances and with the note discovered in the jar of ammonia.  Now, if the prosecutor will be so kind as to let me see that note—­thank you, sir.  This is the identical note.  You have all heard the various theories of the jar and have read the note.  Here it is in plain, cold black and white—­in Dr. Dixon’s own handwriting, as you know, and reads:  ’This will cure your headache.  Dr. Dixon.’”

Alma Willard seemed as one paralysed.  Was Kennedy, who had been engaged by her father to defend her fiance, about to convict him?

“Before we draw the final conclusion,” continued Kennedy gravely, “there are one or two points I wish to elaborate.  Walter, will you open that door into the main hall?”

I did so, and two policemen stepped in with a prisoner.  It was Thurston, but changed almost beyond recognition.  His clothes were worn, his beard shaved off, and he had a generally hunted appearance.

Thurston was visibly nervous.  Apparently he had heard all that Kennedy had said and intended he should hear, for as he entered he almost broke away from the police officers in his eagerness to speak.

“Before God,” he cried dramatically, “I am as innocent as you are of this crime, Professor Kennedy.”

“Are you prepared to swear before me,” almost shouted Kennedy, his eyes blazing, “that you were never served properly by your wife’s lawyers in that suit?”

The man cringed back as if a stinging blow had been delivered between his eyes.  As he met Craig’s fixed glare he knew there was no hope.  Slowly, as if the words were being wrung from him syllable by syllable, he said in a muffled voice: 

“No, I perjured myself.  I was served in that suit.  But—­”

“And you swore falsely before Kimmel that you were not?” persisted Kennedy.

“Yes,” he murmured.  “But—­”

“And you are prepared now to make another affidavit to that effect?”

“Yes,” he replied.  “If—­”

“No buts or ifs, Thurston,” cried Kennedy sarcastically.  “What did you make that affidavit for?  What is your story?”