Branding the method as "junk science," forensic pathologist Raquel Fortun claimed the PNP is also using an obsolete method to determine if a person fired a handgun.
Fortun explained this during her testimony before the Makati City regional trial court last week and stressed both methods of determining the presence of semen called the "Florence Test" and the paraffin test to detect gunpowder burns have been abandoned 50 years ago.
Fortun said the Florence test used by the PNP Crime Laboratory to determine the presence of semen in the complainant’s underwear and the condom allegedly used by one of the suspects in the Subic rape case is a non-specific and unreliable method.
The Florence Test was first introduced in 1896 or two years before the declaration of Philippine independence and is therefore "very, very old," Fortun stressed.
Fortun’s claim of being one of the only two formally trained forensic pathologists in the country caused a stir among her colleagues.
Another forensic pathologist, Ma. Cecilia Lim of the University of the Philippines-Philippine General Hospital (UP-PGH), however, claimed Fortun is only revealing the new trend in forensic science.
Like Fortun, Lim also claimed she had been trained in gathering evidence through the use of modern forensic techniques.
Fortun also wrote an article giving a lengthy discussion on why the Florence Test and the Paraffin test can be called junk science.
In a study she presented in 1966 at the 18th annual meeting of American Academy of Forensic Sciences, Fortun documented how the Paraffin test fails to differentiate people who fired guns against those who didn’t.
Fortun said the PNP should utilize more sensitive tests, as against the traditional paraffin test since the method cannot really determine miscreants aside from torturing the subject by having both his or her hands placed in a molten paraffin wax.
Fortun explained the test was originally known as the "dermal nitrate test" devised by Teodoro Gonzalez of the Mexico City police department in 1933.
The procedure involves the coating of a person’s hand with molten paraffin wax and once it cools, the casts are removed so that the chemical diphenylamine acid can be applied.
"The chemical basis of the test is premised on the presence of nitrates and nitrites that will react to produce a visible blue-violet color change on the wax," Fortun explained in the same way she wrote for the Gaceta del Pilar, the journal of the M. H. Del Pilar College of Law of the Bulacan State University.
"The nitrates and nitrites are believed to have come from the gunpowder or primer inside the bullet casing that ignites as a gun is fired," she said.
Fortun said the method has been abandoned by law enforcement agencies all over the world since its results cannot be of value as it confuses the public, aside from torturing the subject.
Her article noted how a technician drips molten paraffin wax to the hands of an individual who usually suffers serious burns.
Fortun explained soil, water, food, chemicals, and other materials also have nitrates and nitrites which means that false positive results of the test are highly likely.
"The supposed positive blue reaction is also very unreliable," Fortun said, noting that a permanent documentation of this color change is practically not possible because it disappears fast and requires magnification.