Genetic material doesn't lie

Rosie
Rosie Gillingham
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Since the 1980s, DNA has proven to be an indispensible tool in solving crimes

Second in a three-part series

There's a lot more to a crime scene than the chaulk outlines you see on TV.

In almost all crime scenes, something is unwittingly left behind at or removed from, the scene which gives clues and helps piece together the puzzle of what happened and who did it.

The clues can be so small, they're invisible to the naked eye. And that's where science comes in.

Police use several methods to gather evidence at a crime scene, including collecting DNA. Forensics specialists say science is becoming more crucial in the judicial system. Photo by Keith Gosse/The Telegram

Second in a three-part series

There's a lot more to a crime scene than the chaulk outlines you see on TV.

In almost all crime scenes, something is unwittingly left behind at or removed from, the scene which gives clues and helps piece together the puzzle of what happened and who did it.

The clues can be so small, they're invisible to the naked eye. And that's where science comes in.

A single strand of hair, a speck of saliva, a tiny drop of blood or a partial fingerprint can lead investigators to the person responsible for a crime.

Once the evidence is collected, examined and eventually presented in court, it can ultimately lead to a conviction.

In fact, many of the most serious crimes in this province are solved in laboratories thousands of miles away.

"In the judicial system today, science is more important than eye-witness identification," said Sgt. Karl Piercey, a forensics supervisor with the Royal Newfoundland Constabulary in St. John's.

"We're finding some people will see things, but sometimes they're not seeing exactly what happened. They'll see a portion of what happened and fill in the rest."

People's perceptions can be influenced by such things as their emotional state at the time - whether they're under stress or feeling pressured - and their background, such as their age and level of education.

"It can all affect the way people perceive things," Piercey said, "and the way they explain things."

In a world where memories fade, lies are told and stories vary, science can be an investigator's most reliable source for information.

"There are so many variables that come into play and scientific evidence can eliminate a lot of those variables," Piercey said. "Scientific examination is almost infallible in regards to the information it relays."

DNA the most telling evidence

Of all the scientific evidence collected at a crime scene, DNA is one of the most telling.

Deoxyribonucleic acid contains the biological instructions that make each species and individual unique.

It's found in white blood cells, which are not only in blood, but also semen, vaginal secretions, skin, saliva and hair follicles. So, when any of these are left behind, investigators are able to identify a suspect using his or her unique genetic blueprint.

"DNA filled the void which we had in our forensic tool box," said Piercey, a 29-year veteran of the RNC who has been involved in forensics since 1991.

"For the longest time, with the most serious and violent offences against people - murders, assaults, sexual assaults - there was always bodily substances being secreted or shed or left behind, and there was no way to really link it back to a particular person.

"Now we can. DNA filled that hole."

Surprisingly, DNA testing has only been around since the mid-1980s, when a British researcher discovered that each human has unique DNA.

Since then, it has changed the world of crime-scene investigation.

In 1986, that researcher, Alec Jeffreys, used DNA testing to clear a teenager of two murders. It was then used to solve the case. Police in Canada began using the technique in the early 1990s.

Piercey said it was first used in Newfoundland around the mid-1990s.

"Now," Piercey said, "DNA is used in almost every case we investigate."

To collect DNA, crime scene investigators use swabs that have been vacuum-packed and preserved in special cases. The swabs are moistened with water to help dissolve the substance being swabbed. The swab is then sealed in a tube and air-dried to preserve it.

Often substances are collected by cutting them out of material or fabric, like a rug or bed sheet, where they were discovered.

"When we search a crime scene, we're not just searching for blood or anything in particular," Piercey said. "We search for any evidence that may identify someone who was there or tell us what happened there. And they could be anything. Might be some kind of impression or a biological material that was shed."

Everything is photographed and then evidence is collected.

Once DNA samples have been gathered, they are shipped to one of six forensics laboratories across Canada, depending on the specialty required.

The waits for results can be lengthy.

That's what happened in the 2008 Chrissy Predham-Newman murder case. Police were waiting months for lab results before they arrested her estranged husband, Ray Newman.

"Sometimes there are also subsequent submissions," Piercey said, "when you have to wait to get results back from the first submission before you can resubmit more exhibits."

Upon entering a crime scene, Piercey said, officers have to be meticulous in how they collect material, so as not to contaminate any DNA traces.

"So, you can't just pick it up and say, 'Oh, that's got blood on it,' and then lay it down and take a picture of it. The integrity is gone ..." he explained.

"You hear the word contamination all the time, or cross-transfer of evidence. That's something you really have to avoid."

He said DNA testing is so sensitive nowadays that "if you sneezed near (a sample), your DNA would be on it."

For that reason, crime scene investigators wear white protective suits and rubber gloves.

"We can go through a box of rubber gloves in an hour," Piercey said.

Fortunately for the police, DNA can last for years. Investigators have successfully extracted DNA from old blood stains, for example.

rgillingham@thetelegram.com

Geographic location: St. John's, Canada, Newfoundland

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Comments

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Recent comments

  • t
    July 02, 2010 - 13:34

    DNA, witnesses, sworn statements, none of these are any good if the police prefers to believe a lie and a liar rather than honesty and solid evidence. It cost me thousands of dollars to try to get justice for myself and for other people but police turned a blind eye and closed a file and I will never know why. Forgery and fraud is alive and well in this province. Strong words, yes and I would go before any court of law and make the same statement because I would like to see justice prevail and crooks taken off the street.

  • John
    July 02, 2010 - 13:09

    I wonder if a really good hot and bustling, crackling fire fed from efficient fuel could destroy most or all of the evidence. Or perhaps a really well-designed chemical explosion. Or just a really good dousing of acid using a power sprayer.

  • t
    July 01, 2010 - 20:23

    DNA, witnesses, sworn statements, none of these are any good if the police prefers to believe a lie and a liar rather than honesty and solid evidence. It cost me thousands of dollars to try to get justice for myself and for other people but police turned a blind eye and closed a file and I will never know why. Forgery and fraud is alive and well in this province. Strong words, yes and I would go before any court of law and make the same statement because I would like to see justice prevail and crooks taken off the street.

  • John
    July 01, 2010 - 19:44

    I wonder if a really good hot and bustling, crackling fire fed from efficient fuel could destroy most or all of the evidence. Or perhaps a really well-designed chemical explosion. Or just a really good dousing of acid using a power sprayer.