Future forensics: Warrant to search your brain

Electroencephalographic responses and brain fingerprintingâ€"we have a warrant to search your brain.

On the leading edge of forensic science, experts are arguing whether ear prints (the impression eavesdroppers might leave when pressing their ears against a door or window) are a useful way of identifying criminal suspects. In the only U.S. court test so far, an appeals panel in Washington state said last year that there's insufficient scientific backing for the technique. Another topic of debate is lip prints; the science jury is still out. But another kind of oral evidence is well accepted: matching bite marks to the teeth of suspected assailants.

Meanwhile, DNA has become investigators' tool of choice both to identify suspects and to clear the wrongly accused. Researchers also continue to press forward with new tools in other well-established areas of forensic science. One, an off-the-shelf package that combines the capabilities of an electron microscope and a computer workstation, runs fast and intensely detailed studies of gunshot residues, the trace elements that mark someone who has recently fired a gun.

There are always new frontiers and novel techniques. One gaining increasing attention concerns the value of memory as objective evidence. A psychophysiologist who has set up shop in Fairfield, Iowa, Larry Farwell, has devised a technique that he contends can tell whether a criminal suspect's brain harbours details of an offense. He calls it brain fingerprinting.

For those who think memory is a notoriously undependable record of anything, the notion seems unlikely. But Farwell's technique is backed by serious science (it has undergone peer review), and it's getting a serious hearing in court.

This past fall, Farwell used brain fingerprinting to determine whether Terry Harrington, convicted in 1977 of murdering a night watchman at a Council Bluffs, Iowa, car dealership, really committed the crime. Or, to use Farwell's terminology, he used the technique to see whether Harrington's brain stores a record of the killing. His conclusion: Harrington's brain does not carry information about the crime that only the killer would know, but it does include data that tends to support his alibi. A judge is studying Farwell's conclusions and is expected to rule this year on whether Harrington should get a new trial.

Farwell's technique involves seating subjects in front of a computer monitor and fitting them with a headband equipped to pick up brain waves. A stream of words and images are then flashed on the screen, including crime details that only the perpetrator should know. Farwell's apparatus is designed to pick up reactions that scientists believe occur only when a subject recognises a significant memory. Farwell says the activity he looks for "memory and encoding related multifaceted electroencephalographic responses" (MERMER)is proof that a record of the event is stored in the subject's brain.

How can anyone be so confident that a single tool can universally tell the guilty from the innocent? Farwell is winningly optimistic in his answer. Imagine, he suggests, sitting in a room with a friend. Then an elephant walks in. "You are going to notice that an elephant walked in because it's information we need to function properly-- we all need to take note of significant information as it arises, and this is true of all sorts of cultures," he says. "Our responses may be different, but the thing we don't have a choice about is taking in the information."

2003 Interpol presses for a global DNA database of criminal suspects.
2004 US lawmakers call for "unerasable" hard drives to aid in forensics.
2009 Courts accept sniffer analysis: identifying individuals through their body's unique chemical odour.
2021 Neuroscientists demonstrate cerebral image capturing, turning memories into images.
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Talkback 2 comments

    I think that for the sake of f ...Anonymous -- 27/01/05

    I think that for the sake of future forensics i believe that getting a warrent to search someones brain is a great idea. Not only would it save alot of time and effort but it would also save alot of money. Now people from the crime lab spend over a bilion dollars a year to help with investigation. Searching a brain is alot faster and alot cheaper. Alos with nowadays, we don't always get the right guy that is responsible for the crime. with the new technology, there is little chance for error. Plese emaili me if you have questions.

    Brain Fingerprinting Prod Dr P chandra Sekharan -- 02/01/09

    No big argument is necessary to discard brain fingerprinting as a Potemkin science. The Johnnies, who designate their technique as ‘brain-mapping’ or label their technique with an impressive terminology ‘brain electrical oscillation signature profiling’, make use of only the EEG machine to detect the scalp electrical signal output. The signal detected by the scalp electrode is predominated by the excitatory and inhibitory post synaptic potentials on dendrites and neuronal cell bodies, not the deeper axon action potentials.
    Thus EEG is a nonspecific indicator of cerebral function. Any pathophysiological insult to the central nervous system can result in alterations in electrophysiology. Thus with few exceptions does little in providing a precise diagnosis. EEG abnormalities are pronounced with acute injuries of the outer cortex. Disorders affecting deep brain structures or resulting in a chronic indolent loss of neurons may show little to no EE changes.
    A listener who is sitting outside a football stadium cannot see the activity inside but may make some reasonable guesses about the course of the game based on hearing the fluctuating roar of the crowd. This vantage point does not allow the listener to understand fully the details of the game or what individual conversations may be taking place between the coach and players.
    Similarly scalp electrode can detect the fluctuating tonic activity of millions of neurons allowing the electroencephalographer to make some broad assumptions about the functioning of the brain. However this technique is not sensitive to the exquisite detail that is needed to appreciate neural activity associated with cognitive processes or mood states. While this is the correct and latest assessment of EEG even in medical diagnosis, how can our non-medical psychologists claim to read reactions of the brain to pinpoint the guilty person? Another major discrepancy in brain fingerprinting is that the scalp electrode cannot make any distinction between the signals emanated from the brain of the perpetrator and the brain of those who have knowledge about the crime.
    It is also significant to note that a Committee of neuroscientific experts headed by Prof D. Nagaraja, the Vice Chancellor of the National Institute of Mental Health and Neurosciences, Bangalore came out with a clear finding that
    1) Scientific basis for brain fingerprinting as well as the ‘Brain Electrical Oscillation Signature’ is sub-optimal
    2) Peer reviewed publication with relevance to normative data is none
    3) Potential error rate is unknown
    4) Procedural standards need optimization
    5) Scientific acceptance is not unequivocal
    The police should therefore give a rethinking about their habit of running after the Potemkin techniques

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