The nature of the poison used, cyanide of mercury, was also a slight clue, as it is a substance which is not used in medicine and must in all probability have been specially prepared for the purpose, by some one with a good knowledge of chemistry.
At the coroner's inquest, which began on February 9, 1899, certain facts were elicited that tended to bring suspicion on Roland B. Molineux, who was also a member of the Knickerbocker Club and well acquainted with Barnett and Cornish. He was also known to have quarrelled with the latter. At the close of the inquest Molineux was arrested, and removed to the Tombs prison.
Owing to legal technicalities in the original indictment, which charged him with the murder of both Mr. Barnett and Mrs. Adams, he was twice liberated, and then for the third time arrested.
The trial of Molineux for the murder of Mrs. Adams was a memorable one, and lasted nearly three months. It began on November 14, 1899, at the Central Criminal Court, New York, and was not concluded till February 11, 1900.
The evidence was entirely circumstantial. Most of the experts in handwriting who were examined declared that the address on the packet sent to Mr. Cornish was in Molineux's writing, and that he had also written both applications to the druggists in Cincinnati. Further, Molineux was engaged as a chemist to a colour factory in which cyanide of mercury was used, which would enable him either to make or procure that special poison, from which only three other fatal cases had been recorded.
No witnesses were called for the defence, and the jury found Roland B. Molineux guilty of "murder in the first degree," which, according to American law, is murder with premeditation.