The hair revealed where the murder victim once drank water

Scientists at the University of Utah have studied a tool against new crimes by proving human hair that reveals where the person drinks water. Since then help police follow previous actions of suspects or traces of unidentified victims.

The geochemist Thure Cerling - who led the research with ecologist Jim Ehleringer - said: 'What you eat and drink will show you. And those things are recorded on the hair '.

Their findings were published online February 25, 2008 in the Proceedings of the National Academy of Sciences. The method of analyzing new hair samples may also help anthropologists, archaeologists, doctors as well as police.

Ehleringer said: ' We have noticed significant changes in oxygen and hydrogen isotopes in hair fibers as well as water sources related to a person's living place in the United States. The police are using this method to recreate the identity of victims in unexplained murders. '

One of the police officers using the new hair analysis method is detective Todd Park of the Salt Lake County Police Office. He applied a method to identify a murdered woman whose body was found on the Great Salt Lake on October 2000.

Park - a member of the murder department - said: 'This is an extraordinary method. I think it will be very helpful for law enforcement agencies . ' Isotopes are forms of the same chemical element with different molecular weights. Stable isotopes are non-decay isotopes through radioactivity.

Ehleringer is an outstanding professor of biology at the University of Utah, while Cerling is also a leading professor of geology, geophysics and biology. Three years ago they co-founded IsoForensics, Inc. - a company that uses stable isotope analysis of legal substances to find very small differences between different isotopes of the same chemical element.

Cerling and Ehleringer conducted a new study with Lesley Chesson (student of a biology master and technician at the University of Utah and IsoForensics), David Podlesak (postdoctoral researcher at university). Utah and IsoForensics company). Another co-author of the study is postdoctoral researcher Gabriel Bowen, who worked at the University of Utah, and graduate student Adam G. West (now at the University of California - Berkeley).

Ehleringer has previously developed a method that is still being used by the US Drug Administration to understand where cocaine or heroin production is based on local differences in hydrogen, oxygen, nitrogen and carbon isotopes. absorbed into cocoa trees, poppy plants through soil and water. He also analyzed samples of hydrogen isotopes and oxygen to find traces of fake 100-dollar bills based on water samples used to grow cotton to make fake coins.

Diagram of isotope density in hair and water source

The two charts above show the ratio of hydrogen isotopes (pictured above) and oxygen isotopes (pictured below) in human hair throughout the United States. This ratio varies by geographic location due to the difference between the isotope ratios in the local drinking water source. In the chart above, the ratio of heavy and rare hydrogen 2 isotopes as well as the most common, lighter hydrogen hydrogen isotope ratio in orange and red areas; Two types of isotopes have the lowest ratios in green and dark green areas. Also in the chart below, the ratio of heavy, rare oxygen isotopes 18 as well as the most common, slightly higher ratio of oxygen isotopes in orange and red areas; reach the lowest in dark green and green areas. (Photo: University of Utah)

The new method analyzed the stable isotopes of hydrogen (rare hydrogen 2 and common hydrogen 1), oxygen (rare 18 oxygen and common oxygen 18) that appear in growing hair strands. Analytical isotopes are taken from the food and water that a consumer consumes and in the air they breathe.

The ratio of oxygen-18 and oxygen-16 isotopes are the same everywhere. Americans seem to have nearly the same ratios of hydrogen and oxygen isotopes as their diets are gradually becoming similar.

The study also found a close correlation between oxygen and hydrogen isotope ratios in hair and water, 85% difference in isotope ratios in a person's hair all have similar isotope ratios. apply in the water source where the person used to live . So only a small hair can determine a person's position over a period of weeks to years, depending on the length of the hair sample and the length of time that hair grows.

Scientists use this method to produce encrypted maps in the form of colors that show how the ratios of oxygen and hydrogen isotopes change in different areas of the United States. Although the map cannot indicate the location of a person's place in the past, it is possible to map the general geographic area that person used to stay and use the area's drinking water source.

Ehleringer said: 'You will notice the difference between Utah and Texas'. But Cerling said: 'However, you may not be able to distinguish between the city of Chicago and Kansas City.'

The map is based on isotopic analysis of hair and water samples collected at barber shops and from taps of 65 cities in 18 states across the United States. In every city, scientists collect hair samples from about 100,000 people or less to ensure hair samples come from the barber shop but most are from local residents rather than tourists.

Ehleringer's wife Edna and one of her friends collected hair samples in the southern, central and southwestern states of the United States. Cerling's children - Claire and Dylan - traveled throughout the northern part of the country. They asked the barbers: 'Can we get some rubbish on the floor or in the trash?' Jim Ehleringer said: 'Then they came back with cardboard boxes filled with small bottles of water and the envelopes inside with hair left out.'

Why isotope density varies by geography

Why do domestic isotopes - specifically oxygen and hydrogen isotopes - vary by geographic location?

When clouds leave the ocean and enter the continent, rainwater containing oxygen isotopes 18 and hydrogen 2 isotopes tend to fall first because they are heavier. So the ratio of oxygen isotopes 18 and hydrogen isotopes 2 is higher than near the coast, lower than in the more remote areas of the continent compared to the ratio of 16 oxygen isotopes and hydrogen isotopes 1. But the presence of Another factor is equally important. These include the temperature of the cloud, the time when the rain appears as well as the evaporation of water from rocks and plants.

These factors explain why the ratio of oxygen isotopes 18 and hydrogen 2 isotopes in drinking water is reduced when going deep into the continent from the west coast (where cold winter storms are present). while still at a deep level in the territory from the Gulf to the south Atlantic coast (where the clouds have higher temperatures).

Isotope density also varies with rain and snow each season, but drinking water sources in reservoirs or groundwater show average rainfall in an area over time and space.

Drinking water from any area has its own isotopic traces that appear in the developing human hair. The mark is not affected by drinks because 'beer, soft drinks, or milk are mostly from the same area,' Ehleringer said.

The study found that the regions where water and hair samples have the lowest concentrations of hydrogen isotopes and oxygen 18 include northern and western Montana, north-central Idaho and northwest Wyoming. Heavy isotopes have fallen from the clouds before they reach areas deep within the continent for both cold temperatures and the distance from the Pacific Ocean.

The areas with the highest ratios of hydrogen 2 and isotopes 18 in water and hair samples are southern Oklahoma, north central Texas, Florida, southern Georgia and south of South Carolina. The high isotope ratio in these places is high because most of the water is obtained from the summer rains, the lake water evaporates to leave heavy isotopes in the water.

A new tool for police, investigators and scientists

This method has now been used by police to find out where the victims of unspecified assassinations have been located before death.

On October 8, 2000, hunters found the body of a murdered woman near Interstate - 80 along the southern area of ​​the Great Salt Lake on the west side of Salt Lake City. Detectives collected 26 bones, some hair, a T-shirt and a neck strap. A few months later, they recreated the woman's face and made it public throughout the country, but still did not know who it was. He is about 5 feet tall, aged 17 to 20.

Hair revealed where the victim of the murder had been drinking water (Photo: Getty)

Park said: 'We don't know who the victim is. We don't even know the cause of death. '

After hearing about Ehleringer's study, Park contacted him and arranged to conduct isotopic analysis on the victim's hair sample to determine where the victim had arrived before he died. Park said: 'The specimens I gave Jim gave me the taste of the potential for the two years before the victim died. The victim lived in the northwest - mostly in Idaho-Montana-Wyoming area and possibly even Oregon and Washington. '

After the scientists carried out more experiments with oxygen isotopes on the teeth of the victims, isotopes can indicate the location of the teeth as well as where the victim grew. Park will check information about missing people in areas where the victim has gone in the hope of identifying the victim.

The detective said: 'Although a small detail is useful. We put small puzzle pieces next to each other to have an overall picture. And this is how we can get those pieces. '

Another application of this new method is to analyze hair samples of a person or an animal for past actions.

In the study, scientists analyzed hair samples from a person who had moved from Beijing to Salt Lake City. Hair fibers developed during a three-month period before the person moved with relatively high levels of oxygen isotopes 18 and hydrogen isotope 2, reflecting the high density of these isotopes in Beijing's water source. But in the hair that grew around the time after coming to Utah - the density of these isotopes decreased significantly, equivalent to the low rate in Salt Lake City's drinking water source.

Police can use this technique to check an offender's alleged alibi that he was not at the scene of the incident.

Ehleringer said anthropologists and archaeologists could use this method to analyze ancient human hair samples to find out where native Americans had migrated or discovered the lives of testers. Wild Mormon from Missouri state to Utah state. Cerling believes that the analysis of bizong bison's fur samples is likely to reveal many things about their migration patterns when the number of individuals in the herd becomes too much.

To understand why the source of drinking water affects the ratio of isotopes in hair, scientists have had to understand the effect of food on these isotopes in human hair. As a result, archaeologists can analyze human hair or animal hair to quantify protein intake, eat seafood or eat food on the ground; or to determine the social class that people achieve based on high protein animal diets or high levels of green vegetables.

The new method may also bring many medical applications. According to Cerling, because diabetic patients drink a lot of water, the oxygen rate in their hair is also different from those who do not. Ehleringer stressed that hair also records changes in isotope ratios if the disease caused by the diet has worse symptoms.