Fighting crime with science

Rosie Mullaley
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Why hair, bones and teeth contain geographic clues

First in a three-part series
For years, stable isotope analysis has been used to test soil and water and to track migratory patterns.

Now, it's being used to fight crime in this province - a fairly new development in the field of forensic chemistry in Canada.

Dr. Vaughan Grimes, assistant professor in the Department of Archeology at Memorial University, explains the scientific technique, called stable isotope analysis, Thursday during a news conference at RNC headquarters. - Photo by Keith Gosse/The Telegram

First in a three-part series

For years, stable isotope analysis has been used to test soil and water and to track migratory patterns.

Now, it's being used to fight crime in this province - a fairly new development in the field of forensic chemistry in Canada.

Stable isotope analysis has been used in archeology, ecology, environmental science, geochemistry and medical research, as well as by police forces across the United States in the last decade.

Thursday's announcement at the Royal Newfoundland Constabulary headquarters is believed to mark the first time it's being used in a criminal investigation north of the border.

By examining isotopes - varying atoms of the same elements, such as oxygen or hydrogen - from bones, hair and teeth in human remains, scientists are able to answer questions about a person's geographic location.

While the technique doesn't reveal a person's identification, it does help police determine who they are dealing with by narrowing down the area where they lived or stayed in the course of their lifetime.

"In criminology, police look at every possible tool they can get their hands on," Dr. Henry Schwarcz, who specializes in isotope analysis at McMaster University in Hamilton, Ont., told The Telegram earlier this week.

"Stable isotope analysis is one of those tools in the tool kit of the crime-solving profession. ...

"Think of isotopes as a kind of fingerprint. ... It can't tell you about a person's lifestyle, but there's geographical value in studying isotopes."

Schwarcz - a professor of geography and geology - has been recruited by several police forces in the United States during the past few years to help solve criminal cases. Most of them involved the discovery of human remains.

In 2006, the Mammoth Lakes Police Department in California looked to Schwarcz to answer questions about an unidentified murder victim, whose remains were found with no indication of who she was.

"By studying the isotopes from her teeth and bones," he said, "we were able to determine she was from northern Mexico."

Further DNA testing determined she had lived in Oaxaca, Mexico.

To understand how scientists are able to pinpoint people's origins, you have to know how isotopes work.

Schwarcz spells it out in an article headlined "Tracing unidentified skeletons using stable isotopes," which was published in Forensics Magazine (June 2007).

He explains that the body is made up of atoms and the atoms of almost all chemical elements (carbon, oxygen, hydrogen) have more than one possible atomic weight. Different atoms of the same element are called isotopes.

Oxygen, for example, has three naturally occurring isotopes - O-16, O-17 and O-18. These isotopes are stable, meaning they never disintegrate.

However, natural processes can cause tiny variations. For example, the O-18 and O-16 ratio in rain and snow varies by up to three per cent, depending on where it fell. It's measured using a stable isotope ratio mass spectrometer, which separates the different isotopes of an element.

"These analyses give the degree to which a sample is enriched or depleted in O-18 compared to the world standard," Schwarcz wrote.

Since oxygen atoms come from the water we drink, scientists can learn where a person lived from the isotopic composition of their teeth and bones, even in cases where remains have been burned.

"O-18 generally decreases from the equator to the Poles," he said, "and from the west coast of the continent to the interior."

Schwarcz used the technique years ago to trace the migration history of people found at archeological sites.

Dr. Thuree Cerling, a distinguished professor of geology, geophysics and biology at the University of Utah, has also done extensive research using isotope analysis.

"You are what you eat and drink," Cerling said.

He explained that the kinds of plants in a person's diet affects the ratios of carbon in the body, while different kinds of fish affect the levels of nitrogen.

It's oxygen, found in water, though, that is the best indicator, Cerling said.

Local water supplies have isotope signatures that are incorporated into bones, hair and teeth.

"Basically, warmer parts of the planet have more O-18 than colder parts," Cerling told The Telegram.

He is the co-founder of IsoForensics Inc., a company that specializes in stable isotope analysis.

"If you only drink Coke, well that's made with local water. Just like when you make pasta, it's made with tap water."

Cerling expects stable isotope analysis to be used more often to solve crimes in the coming years.

In the U.S., it's been used in the identification of drug trafficking routes by comparing the levels of isotopes in morphine grown from poppies in Southeast Asia and Southwest Asia, as well as cocaine from Bolivia and Colombia.

To break up counterfeit rings, the isotope levels in cotton fibres in $100 bills have been analyzed to determine their geographic origin.

The technique can also help forensic investigators determine whether two or more samples of explosives are of a common origin, since most explosives contain carbon, hydrogen, nitrogen and oxygen atoms.

Stable isotope analysis was key in uncovering more clues in the mystery surrounding a human skull that was found on Minerals Road in Conception Bay South almost a decade ago.

At a news conference at RNC headquarters Thursday, investigators announced the technique was key in helping them determine the recent whereabouts of the victim, who police believe was murdered.

Through stable isotope analysis, it was determined the victim resided for extended periods of time in southern Ontario or southern Quebec, and/or Atlantic Canada or possibly the north-eastern United States.

He is believed to be a white male who may have visited Newfoundland for a brief period about 13 months prior to his death.

From a scientific technique called carbon-14 bomb-pulse dating - which examines the carbon-14 levels in tooth enamel and hair - investigators were able to determine the victim was born between 1955 and 1961.

It's estimated he died between 1994 and 1997.

Dr. Vaughan Grimes, assistant professor in the Department of Archeology at Memorial University, said in analyzing the skull, they were able to answer questions about the man's, thus narrowing in on the locations he likely spent time.

However, he said it was the hair that was "particularly telling" about where the man had been in recent years.

"He conveniently had long hair," said Grimes, who said hair grows about one centimetre per month.

With the use of diagrams, he explained that the carbon levels and isotopes in hair corresponds with varying geographic locations in North America, which is how they were able to determine which areas he spent time over the past number of years.

Science, in general, has played a big role in criminal investigations. In part two of the series, find out how science is helping our own police officers fight crime.

Organizations: The Telegram, McMaster University, Mammoth Lakes Police Department University of Utah IsoForensics Department of Archeology

Geographic location: California, United States, Atlantic Canada Hamilton Northern Mexico Oaxaca Mexico Southeast Asia Southwest Asia Bolivia Colombia Minerals Road Southern Ontario Southern Quebec Newfoundland North America

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