The mysterious death of Francesco I de' Medici and Bianca Cappello: an arsenic murder?

Dear Editor,

In reply to the letter “The mystery of beard hair” of Prof. Gino
Fornaciari, we would like to comment as follows.

The small skin fragment, not larger than 2 mm in diameter, was
discovered and removed by one of the authors (EB) from the
maxillary bone of Francesco I. This happened before the
intervention of paleopathologists in the exhumation, to be precise
while Prof. Fornaciari was dutifully talking, as scientific director of
the Medici’s project, with the press. Actually, Prof. Fornaciari
should remember that later that morning some organic material
different from bones (he defined it a “tendon or cartilage fragment”)
was also discovered in the coffin, but at that time it was not
collected for DNA analysis, because nobody expected that it could
be compared with viscera, not yet discovered. In addition, it is
more than plausible that, even after complete ossification, small
skin fragments may still remain on bones. The skin fragment had a
couple of hairs still attached. Other few hairs were collected by EB
and DL under the skull, on the bottom of the small zinc coffin
containing Francesco I bones.

DNA analysis was performed using microsatellite DNA
methodology. It was carried out by two different laboratories that
analyse ALSO modern DNA. They are ISO 9001 certified
laboratories whose performance and quality are beyond
discussion. All the recommendations of the International Society
for Forensic Genetics have been followed, including analysis of
negative controls. A “laboratory designed for ancient DNA
manipulation” is strictly necessary in the case of mitochondrial
DNA which is particularly prone to contamination. In our case
nuclear DNA was available which was fairly well preserved.

The organ fragments discovered in Bonistallo were presumably
collected during the autopsy of Francesco I and Bianca Cappello,
that is BEFORE any POTENTIAL embalming procedure was
carried out on the corpses. In addition, there is no evidence that
preserving fluids were used on viscera and, even if used, no
evidence that they contained arsenic. Actually, if any
arsenic-containing preserving fluid was used, we should have
likely found much higher arsenic levels in the organs.

The biological fragments were found in a small hollow (40 cm
width) under the floor of the Church of Bonistallo: the hollow was
full of masonry debris, mixed up with stones, dating back to
previous investigations (quoted by Saltini-1898; Mons. Landini
1903; 1950). In this context two matching crucifixes (whose design
is referable to the time of the Granducal couple’s death) were also
found which, in our opinion, are strongly suggestive of our
discover, but their dating has no influence and does not
compromise the identification of the organic fragments.

It is more than logical that, when an important scientific finding
clashes with the deep-rooted beliefs of historians, the debate
catches fire reaching levels not always at scientific height. It is
worth mentioning, to this regard, the endless controversy, still
unresolved, on the supposed arsenic poisoning of Napoleon.

Competing interests:
None declared