Genes can pinpoint the time of death of crime victims to within close to an HOUR in major CSI breakthrough

Forensics teams currently work out time of death using their body temperature
However, scientists say genes may provide a better way to pinpoint a death time
New research in Barcelona identified 187 important genes after death to do this

Genetic clocks that begin ticking after someone dies could help CSI teams better pinpoint time of death.

Forensics teams currently work out when someone has died using their body temperature, which falls by 1.5°C (2.7°F) an hour.

They can also guess it based on rigor mortis or using insects around the corpse.

But a new study claims genes could provide a simpler way to pinpoint a time of death to within close to an hour.

Murder investigations could be easier in future, as clues in our genes reveal time of death within close to an hour. Forensics teams currently work out when someone has died using their body temperature, which falls by 1.5°C (2.7°F) an hour

Scientists have found a 'cascade' of genetic changes which happen when we die, which fuel the death of cells in the body and the shutdown of the immune system.

The clearest readings come from the skin, thyroid, subcutaneous fat and lungs, as genes no longer need to ferry oxygen from the lung to the rest of the body.

The researchers, who examined genes in 129 dead bodies, say they came up with a time of death accurate to within 63.75 minutes.

They say the method could be a 'powerful tool', noting that current forensic techniques may be unreliable and inaccurate.

However researchers, led by the Centre for Genomic Regulation in Barcelona, stress that their findings have not yet been proven to work beyond 24 hours after death.

Lead author Dr Pedro Ferreira, from the University of Porto in Portugal, said: 'We found that many genes change expression over relatively short post-mortem intervals, in a largely tissue specific manner.

'This information helps us to better understand variation and also it allows us to identify the transcriptional events triggered by death in an organism.'

Changes in the genes begin as soon as someone dies, with the most obvious ones seen between seven and 14 hours later.

Tissues in the body respond in different ways, with the brain showing little change whereas the best readings come from the lungs and thyroid, amongst other things. The researchers say the method has not yet been proven to work beyond 24 hours after death (stock)

While there are few immediate changes in areas of the body such as the spleen and the brain's cerebellum, big changes are seen in the muscle and colon for example.

The study looked at gene expression – the process by which the instructions in our genes are converted into a functional product, like a protein.

They identified 187 important genes after death, including the HBA1 and HBA2 genes which transport oxygen from the lungs and change their behaviour after someone stops breathing.

Working out the time of death is described as a 'problem of central importance' in the study, which is published in the journal Nature Communications.

The authors add: 'Traditional methods for this task rely on physical modifications observed on the body, including algor, livor and rigor mortis. However these approaches may be unreliable or inaccurate.'

Rigor mortis, where the muscles stiffen or relax after death, provides the current best time of death.

But the new genetic method uses tissue which is easily available, offering more options in crime cases where remains are found instead of a whole body.

HOW CAN GENES PINPOINT THE TIME OF DEATH?

Genes may help pinpoint a crime victim's time of death, scientists claim.

Researchers recently looked at 9,000 samples from 36 different type of bodily tissue from donated cadavers.

For each sample, the scientists knew how long had passed between death and the preservation of the body.

Researchers found that after death, different tissues responded in a wide variety of ways.

Some genes, for example, can continue to work for up to four days in a last-ditch attempt to save their cells - despite the death of the host.

Some genes can continue to work for up to four days in a last-ditch attempt to save their cells - despite the death of the host. Researchers use levels of RNA to see better determine a cause of death (stock)

While the clearest readings come from the skin, thyroid, subcutaneous fat and lungs, the readings for the spleen and brain changed very little after death.

To find out how gene expression changed once a person had died, the research team compared blood samples ante-mortem (before death) and post-mortem (after death).

By doing this, the researchers found a 'cascade' of genetic changes that fuel the death of cells in the body and the shutdown of the immune system.

These cascades involved a chemical called RNA, a molecule which is very similar to DNA, but does not form the famous double-helix structure.

RNA is heavily involved in turning our genetic code into usable materials, such as proteins.

In order to gain an idea of activity decrease in the different tissues of the body after death, researchers looked at the levels of RNA.

They found the decrease in RNA levels was consistent and could be used to accurately trace back to the time of death.

Although it isn't ready to be used in the field yet, the levels of RNA were found to be consistent across several different corpses.

Scientists believe they can use these readings to predict time of death to within an hour.

However researchers, led by the Centre for Genomic Regulation in Barcelona, stress that their findings have not yet been proven to work beyond 24 hours after death.