After the inspection and photographic survey of the item, we proceeded to the laboratory analysis, as shall now be described.
We emphasize that the counters, shelves, and all equipment present in the laboratory where the items were viewed had been previously treated with 10% sodium hypochlorite solution, washed with water and finally with 70% ethanol, as unanimously recommended and practiced by molecular biology laboratories (Hayatsu H. et al., 1971; Prince A.M., Andrus L., 1992; Schmidt T. et al., 1995; Whiteman M. et al., 1997; Ohnishi S. et al., 2002; Whiteman M. et al., 2002; Kemp B. M,. Glenn Smith D., 2005; Frégeau C.J. 2008; Caragine T. et al., 2008; Toothman M.H. et al., 2008).
It is recorded that while the tests were being carried out, all those present wore masks, disposable gowns, and disposable gloves.
All the manual operations (from opening of the items, to extemporaneous investigations, to the taking of samples) were performed by one of the experts (Prof. Carla Vecchiotti), with the assistance of a technical collaborator, as authorized by the Corte d’Assise, and it should be noted that during each individual phase, the disposable gloves were changed.
On the basis of photographic comparison with the images included in the RTIGF [=Technical Report on the Forensic Genetic Tests] and specific indications by Dr. Stefanoni, the previously-examined areas on the item were identified for the taking of new samples.
The areas of interest were indicated with the same letters assigned by Dr. Stefanoni.
Thus, the areas on the handle of the knife were indicated with the letters A-D-F, while the areas of interest on the blade were indicated with the letters B-C-E-G.
With the agreement of the parties, two further samples were taken from the point of contact between the blade and the handle, on opposite sides of the knife, and these samples were indicated with the letters H-I.
On each individual area of interest, we proceeded to perform the generic test for blood.
The test was conducted by means of reactive strips [strisce reattive] soaked with dimethyl-dihydro-peroxysan [dimetil-diidro-perossiesano]
and a colorimetric indicator (tetramethylbenzidine) which, in the presence of hemoglobin, assume a green-blue coloration (“Combur Test® E” Roche Diagnostics GmbH, Mannheim, Germany; product code 11896857191, site no. 20212701).
The test requires the reactive area of the strip to be first dampened with distilled water and then put into contact with the surface to be tested, causing a slight rubbing. Within 60 seconds, in the case of a positive result, the reactive area of the strip will assume a green-blue coloration, while any color variations occurring after an interval of two minutes from the test are not significant.
The following results were obtained:
Generic test for blood
Trace A = negative reaction
Trace B = negative reaction
Trace C = negative reaction
Trace D = negative reaction
Trace E = negative reaction
Trace F = negative reaction
Trace G = negative reaction
Trace H = negative reaction
Trace I = negative reaction
The results obtained were documented photographically.
On these same areas, then, samples were taken using sterile swabs (in individual sealed packaging, opened at the very moment of sampling), damp with sterile bidistilled water.
Nine samples were taken, of which seven corresponded to the areas already examined by Dr. Stefanoni (letters A-B-C-D-E-F-G) and two corresponded to the point of contact — not analyzed by Dr. Stefanoni — between the blade and the handle of the knife (letters H-I).
Each individual swab was immediately inserted into the appropriate tube, on which the letter corresponding to the extraction site had been placed.
We note once again that the above operations were performed while wearing masks, disposable gowns, and disposable gloves, which were regularly changed between one sampling and the next.
When the extraction operations were complete, the knife was wrapped in a sheet of tissue paper, inserted in a paper bag, and placed inside the original box, in which the plastic bag that the item had originally been sealed in was separately placed. The box was closed by means of adhesive tape of brown color, on which the signatures of the consultants for the parties and the experts were attached.
We then proceeded to the inspection and subsequent opening of Item 165B.