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Probability blood wasn't from alleged victim? One in 1.6 quintillion, says forensic expert

Other DNA was also found on Zachary Torcaso's Brewers jacket
2016-05-08 Janes Walk DMH-14
File photo. Donna Hopper/SooToday

A blood sample taken from clothing seized from one of the accused charged in connection with a break-in and assaults nearly three years ago revealed a strong genetic match to complainant Ryan Gridzak, jurors heard Monday.

Forensic scientist Michael Bissonnette testified at the trial of two Sault Ste. Marie men about DNA tests the Forensic Sciences Centre conducted for the city police following the March 15, 2014 incident.

He told assistant Crown attorney David Didiodato that a blood sample from a jacket seized from Zachary Torcaso, one of the two defendants, the night he was arrested was analyzed for a DNA profile.

The analysis concluded that Gridzak couldn't be excluded as the source of the blood located on the sleeve of the blue and yellow Brewers jacket.

Bissonnette said that the probability that the blood came from someone else, other than Gridzak, and that it matched an unrelated individual, is one in 1.6 quintillion — the number one followed by 18 zeroes.

Torcaso has pleaded not guilty to two counts of assault and single counts of break and enter to commit the indictable offence of mischief and threatening.

His co-accused Dereck Maione faces three charges and entered not guilty pleas to counts of break and enter to commit an indictable offence, possession of a dangerous weapon (a knife) and committing an assault while carrying the weapon.

The trial started Wednesday, with the Crown calling its first witness, investigating officer Const. John Mclean, but after an issue arose Superior Court Justice Michael Varpio sent the six-woman, six-man jury home until Monday.

Bissonnette, who is with the forensic sciences' Northern Laboratory in the Sault, testified that examination of the jacket was done by a scientist in the centre's Toronto facility, but he reviewed the report and its conclusions, which he supports.

Designated by the court as an expert in forensic biology, DNA collection, analysis and interpretation, he told jurors that police provided the centre with a pair of pants and a jacket, belonging to Torcaso, and a consent DNA sample from Gridzak, for examination.

The blood sample on the jacket had a mixture of DNA from at least three people, but one person, a male, was interpreted as the major DNA profile suitable for comparison, the court heard.

When cross-examined by Eric McCooeye, Torcaso's lawyer, Bissonnette said he doesn't know how the other DNA from two other people got there, but suggested it could be additional traces of blood, skin cells or small amounts of saliva.

He agreed he didn't find any DNA related to Torcaso on the items and only knew who wore the jacket because that is what police indicated.

Comparison samples from the two accused or others were not provided for testing, and the lab routinely doesn't ask for such samples, the witness indicated.

The seized pants weren't tested for DNA analysis.

The court isn't sitting today, but the trial resumes Wednesday with Gridzak on the witness stand.


About the Author: Linda Richardson

Linda Richardson is a freelance journalist who has been covering Sault Ste. Marie's courts and other local news for more than 35 years.
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