Science and the Criminal

by C. Ainsworth Mitchell

For the defence it was urged that death was due to acute gastritis, which was the result of a chill or improper food, and that arsenical poisoning was not the cause; that the fly-papers had been purchased by the prisoner for the preparation of a cosmetic for the face; and that the presence of traces of arsenic in the body was fully accounted for by the fact that Mr. Maybrick was an arsenic eater.

Several medical men expressed opinions strongly opposed to the views of the prosecution, and it was pointed out by these that many of the symptoms characteristic of poisoning by arsenic had not been observed in this case. At the same time it was admitted that the effects produced by arsenic were often erratic, and, as Dr. Stevenson stated in his evidence for the prosecution, “There is no distinctive diagnostic symptom of arsenical poisoning. The diagnostic thing is finding the arsenic.”

The medical experts who gave evidence upon behalf of the prisoner were Dr. Tidy (who, like Dr. Stevenson, was an official analyst to the Home Office), Dr. Macnamara, and Professor Paul; and their view, which was strongly expressed, was that all the symptoms which had been described to them in the evidence pointed against arsenic having been the cause of death.

The judge, in his summing up of the medical evidence, pointed out that expert witnesses were liable at times to take up the position of advocates with regard to scientific matters, and he warned the jury to take this into consideration in forming their conclusions.

The analytical evidence as to the presence of arsenic in the body and in the food and medicine was given by Dr. Stevenson and by Mr. Davis.

Davis had found no arsenic in the stomach, but it was discovered in the liver and intestines. In the bottle of the meat juice he had found half a grain in solution. Arsenic was present in the glass of the bottle, but to a less extent than in the glass of another bottle of the meat juice, in the contents of which no arsenic was present. Hence the glass could not have been the source of the arsenic found in the other bottle.

He had also found arsenic in a glass of milk in the house, in a vessel in which luncheon had been sent to the office of Mr. Maybrick, in a medicine bottle, and in a bottle of glycerine in the lavatory. In fact, one of the most remarkable features of this case was the number of articles in which arsenic had been discovered. Dr. Stevenson had also found no arsenic in the stomach, but had detected a small quantity in the kidney and the intestines. In a portion of the liver he found an amount which he calculated to amount to one-third of a grain for the whole liver, and he gave as his opinion that “the body at the time of death probably contained approximately a fatal dose of arsenic.”

Dr. Tidy, in giving evidence on behalf of the accused, criticised this evidence of Stevenson on the grounds that it did not necessarily follow that because one portion of the liver contained so much arsenic, the same proportion must be present in the remainder. In his experience the amounts of arsenic retained might vary in different parts of the same organ. He calculated from the results of Stevenson’s analyses that the total amount of arsenic was 0·082 grains.

If we examine this evidence more closely it is difficult to see upon what basis Tidy calculated his total. Stevenson had examined approximately one quarter of the liver, and had extracted from two portions a total quantity of 0·076 grains, so that, according to Tidy, the remaining three-quarters could only have contained 0·006 grains of arsenic. On the face of it this seems an absurd conclusion.

The evidence of Professor Paul went to prove that arsenic was present in the material of earthenware vessels similar to that in which the lunch was sent to Mr. Maybrick’s office, and that it could be liberated by the action of an acid, so that the arsenic found in the particular vessel might have originated from the action of acids in the food itself upon the interior of the vessel.