Lino was brought before the Mayor of Boston and then, by his order, he was delivered over to Constable Blayney to escort him back to Philadelphia. As they started back south, Blayney told Lino that whatever he wanted, he need but mention it and his requests would be complied with. In this, Blayney acted the part of a gentleman, but Lino believed that the innate principles of honor and propriety, which existed in the constable, must long since have been corrupted by the baseness of his occupation. This belief put Lino on guard and brought him to the resolution of placing no confidence in Blayney.
On the steamboat from Providence to New York, Lino tried to talk to him, but they could not understand each other. In one of the attempts at conversation, Blayney asked Lino something about arsenic, Lino, fearing he did not understand what Blayney had said, asked if "it was a white powder, good to kill rats." To this Blayney said, "yes, and men too if they take it." At another time, in answer to a question from Blayney about whether he knew if Mrs. Chapman had poisoned her husband, Lino said he knew nothing about it.
Constable Blayney remembered the conversation differently. He had asked Lino if he had a medicine chest. He said he had, but had left it in the Boston jail. Blayney asked him whether he had arsenic in it. He said he had medicine or stuff in it that would kill people and kill rats. Did he give any of the medicine to Mr. Chapman? No, he was innocent he said.
At the time of his arrest in Boston, Lino had three small vials which he claimed were one of essence of cinnamon, one of essence of lemon, and one of extract of bark. He said they were used to ease the frequent pains he experienced. The constable who arrested him, having found these vials, spread the report that he had found three bottles of arsenical waters in Lino's trunk. On arriving in Philadelphia, Blayney spread a similar report and communicated to the mayor about the discovery of the vials and their contents. Lino maintained that he never made any kind of confession or knew anything of Mr. Chapman's death.
It was discovered that on Thursday, 16 June, a day prior to the onset of William's illness, Lino and Lucretia had gone to Philadelphia. When Lucretia went to attend to some personal business, Lino went into a pharmacy, across from Mr. Watkinson's, the tailor, shop. The drug store was owned by Elias Durand, an immigrant from France. Lino asked him, in Spanish, if he could speak Spanish. Durand referred him to his assistant, Mr. Alfred Guillou, who he said was acquainted with that language. Lino asked Guillou, in Spanish, if they had any arsenical soap, for the preparation of birds [Note: Mixtures of arsenic and soap were sometimes used to bathe the insides of a specimen in order to prevent decomposition and insect infestation. This method, invented by the French ornithologist Jean-Baptiste Becoeur (1718 – 1777), was especially popular with taxidermists]. Guillou replied that he did not, but that he could prepare it. Lino said if they had the powder, that would suffice. He asked the price per pound, which was half a dollar. Lino purchased about four ounces.
To investigate the possibility of murder by arsenic, Deputy Attorney General Ross requested that an examination of the body of William be performed. He contacted Dr. John P. Hopkinson, a surgeon at the University of Pennsylvania Medical School. On 21 September, he proceeded to do so. The coffin was removed from the grave and the lid taken off. The body was taken and Dr. Reynell Coates, a general practitioner in the county, was asked to assist. They performed a thorough autopsy and dissection in an effort to determine the cause of death (I will not go into the details of that examination).
The coffin was closed and the body reinterred.
Judging from the appearance of the body and the results of his examination, Dr. Hopkinson attributed William's death to the action of some violent substance on the stomach. By a violent substance, he clarified, he meant a substance usually termed poison. He had never known a case of cholera morbus to terminate fatally, neither in his own practice, nor in that of the friends he consulted. From what he saw, Dr. Coates was also of the opinion that William died by the action of some corrosive poison, or irritant poison, probably of an arsenical character.
Dr. Hopkinson delivered a jar containing William's stomach and about six inches of the intestine nearest the stomach, called the duodenum, to Dr. John K. Mitchell. He was a practitioner of medicine, a lecturer on chemistry, and one of the attending physicians of the Pennsylvania Hospital, an institution which had been co-founded by Benjamin Franklin in 1751. Dr. Mitchell then performed a wide variety of tests in his laboratory. He concluded that after a careful and considerate view of the whole ground, he was unable to resist the conclusion that William died because of the presence of arsenic in his stomach.
Thomas G. Clemson had been summoned by Dr. Hopkinson to assist in the examination of William's stomach with him and Dr. Mitchell. Clemson had studied chemistry in the United States and Europe before becoming an assayer at the U.S. Mint. During one test, an odor of arsenic struck him. He looked around and asked if any one else was burning arsenic? He called Dr. Hopkinson and Dr. Mitchell to smell the odor and they all agreed it smelled of arsenic. No other substance, in his opinion, has the same odor, or one resembling, that of arsenic.
The conclusion that the doctors came to was that William had, in fact, been poisoned by arsenic. Now the question was how and by whom?