What motivates a sex offender to do charity work is an important question; various agencies involved will be reeling from the continuing spate of allegations regarding Jimmy Savile.

It is well known that sex offenders often target deserving causes, in order to get close to a pool of vulnerable victims. Such predators appear outwardly altruistic, in order to gain access.

But in the case of recent allegations over Jimmy Savile, who it is suggested may have raised around £40 million for charity over a lifetime of apparently 'good works', and who seemed to labour for so many different causes, over decades, this doesn't seem an adequate explanation. It could be charity work acts as a smoke screen which fulfils many other warped objectives as well.

In order for aid organizations to screen out and defend against this kind of infiltration, getting inside the mind of the 'tainted altruist', could be vital in order to prevent future scandals.

British psychologists Samantha Craven, Sarah Brown and Elizabeth Gilchrist have recently published an academic paper entitled 'Sexual grooming of children: Review of literature and theoretical considerations', where they point out that the field now regards 'grooming the environment' as a key aspect of sex offender's behaviour. Yet this might be overlooked while charities are being vigilant for grooming of children.

'Grooming the environment' may be a more powerful and damaging strategy, as the recent scandal might be illuminating.

'Grooming' is a strategic pattern whereby sex offenders create trust in victims, and guardians, preparing the groundwork for the future crimes. Charitable work in malevolent hands could be a form of grooming, because it seems one of the most reliable ways of generating an aura of trustworthiness.

Craven and colleagues report 'grooming the environment' means offenders are charming, helpful, and worm their way into 'insider' status.

Savile possibly illustrates this process par excellence, when he was invited to help run Broadmoor Hospital in the 1980's, thereby being put in an ultimate 'insider' position, advising on how sex offenders should be managed.

Craven, Brown and Gilchrist's paper, published in the Journal of Sexual Aggression, points out it is already known these predators possess an uncanny ability to 'read' potential victims, targeting those least likely to complain afterwards, by, for example, noticing who is more isolated.

But offenders are also able to read the community like a book, cannily assessing what needs require fulfilling, in order to make themselves indispensable. One intriguing implication is more vigilance for the character in our midst who is 'too good to be true'; readily undertaking jobs that others won't do.

So, as some have already suggested, perhaps an exceptional alleged case like Jimmy Savile was kind of 'grooming the nation'. Perhaps this kind of sex offender creates a heroic persona through all that apparent self-sacrifice which elevates their status and means the authorities are more likely to turn a blind eye. No one would believe such a champion of the unfortunate, could be capable of anything so terrible as exploiting them.

But at a deeper level this scandal might be about 'self-grooming'. Sex offenders admit to grooming themselves so denying their criminal activity. They pretend to themselves that the child seduced them.

Liz Gilchrist, Professor of Forensic Psychology at Glasgow Caledonian University, speculates a case involving extensive charitable work with children may reflect this factor. She points out that a frequent finding with child sexual abusers is an excessive and inappropriate 'emotional identification' with children.

Such predators are particularly skilled at using children's natural vulnerabilities against them because of their intuitive understanding. For instance, children very often have a strong desire to protect their parents. When the offender explains that their parents would be very hurt if they found out what had been happening, children frequently remain silent. The same may apply if the offender remarks that the hospital or charity which has assisted the child would be similarly distressed.

Craven, Brown and Gilchrist's paper points out that one previous study found 82% of children delayed or did not report an event that they had witnessed, because the thief in the scenario asked them not to tell anyone. This was a stranger, to whom the children had no allegiance - so children would be even more likely to protect a known and respected adult. Sex offenders who exceptionally do a lot of child charity work, may have had an intuitive sense of how willing and capable children are at keeping secrets.

Such sex offenders may be especially able to identify vulnerabilities in others because they themselves are psychologically damaged, and thus recognize these signs in others.

Professor Gilchrist also wonders if it's possible a lot of charity work and lauding from the community feeds into a possible self concept of certain kinds of offenders, encouraging an element of grandiosity. This might explain the 'playing god' aspect of charitable work, but also link to a sense of entitlement in terms of sexual gratification with available youngsters.

Professor Gilcrhist suggests it could also have been that some sex offenders view the adult world as dangerous if too exposed to it, so they prefer to both work and sexually engage with a more vulnerable and less critical group, e.g. the disadvantaged, the sick and children.

It is possible that charitable work gets implicated in this 'self-grooming' because it helps the perpetrator believe that being such a 'good' person and being lauded by everyone else, they couldn't possibly be doing anything wrong. Maybe they even rationalise to themselves that they deserve some kind of 'recompense' for all their hard work, in the form of some kind of earned right to abuse.

Perhaps even a strange sense of guilt over the bad they are doing, is partly assuaged in the minds of 'altruistic' sex offenders by the 'balancing' effect of the 'good' they believe they are achieving, with their charity work.

Those with a special affinity for the disadvantaged are not therefore much less likely to commit abuse, as maybe was previously thought. This widespread erroneous belief may have partly insulated a possibly exceptional offender such as Savile is alleged to be, from investigation until after he died. Particular perpetrators' astounding abilities to avoid detection for so long must have something to do with psychology and manipulation. The urgent need to develop a better psychological understanding is because of the question: how many others are there out there, still performing their heinous crimes undetected?