‘Munchausen's syndrome by proxy’ describes women alleged to have fabricated or induced illnesses in children under their care, purportedly to attract attention. Where conclusive evidence of guilt exists the condition's aetiology remains speculative, but when evidence is lacking diagnosis hinges upon denial of wrong-doing, which is conduct also compatible with innocence. Given those criteria, how can investigators find objective evidence of guilt or innocence?

Professor Sean Spence, who has pioneered the use of functional Magnetic Resonance Imaging (fMRI) to detect lies, carried out groundbreaking experiments on a woman who was sentenced to four years in prison for poisoning a child in her care but protested her innocence.

Using the technology, Professor Spence examined the woman´s brain activity as she alternately confirmed her account of events and that of her accusers. The tests demonstrated that when she agreed with her accusers´ account of events she activated extensive regions of her frontal lobes and also took significantly longer to respond – these findings have previously been found to be consistent with false or untrue statements.

Although the technology has previously been claimed to be 90% accurate - far better than polygraph tests – its use has also been open to debate. Lie detection tests are already used regularly in parts of the US justice system, as well as by businesses. But these are the first brain scanning tests of their kind, carried out on a real-life case, reported in the world literature.

Professor Spence said: "This research provides a fresh opportunity for the British legal system as it has the potential to reduce the number of miscarriages of justice. However, it is important to note that, at the moment, this research doesn´t prove that this woman is innocent. Instead, what it clearly demonstrates is that her brain responds as if she were innocent."

"If proved to be accurate, and these findings replicated, this technology could be used alongside other factors to address questions of guilt versus innocence."

Article: "‘Munchausen's syndrome by proxy’ or a ‘miscarriage of justice’? An initial application of functional neuroimaging to the question of guilt versus innocence", European Psychiatry, doi:10.1016/j.eurpsy.2007.09.001