Child sex abuse is shocking enough but when the perpetrator is a woman it is harder for society to accept because it seems to challenge the nurturing sense of motherhood.
The crimes of nursery worker Vanessa George (pictured) and co-defendants Tracy Dawber and Tracey Lyons shocked the nation.
And more recently Marie Black was the "mistress" at the centre of a child abuse ring where two boys and three girls were raped and abused in Norfolk.
Although women paedophiles are rare, they do exist and can work in tandem with a male accomplice.
This was a common feature in the most high-profile cases, such as Rosemary West, who helped her husband Fred to rape, torture and murder children and women, and Myra Hindley, who murdered and sexually assaulted five children alongside Ian Brady.
Detective Inspector Andrea Kingdon of Devon and Cornwall Police's child exploitation unit, helped bring Sarah Gotham to justice.
"It is rare and I think there is still a perception and a lack of willingness to accept that women will engage in that sort of behaviour," she said.
Dr Sharon Lambert of University College Cork has carried out extensive research into women paedophiles and said denying their sexual motivations did a disservice to victims.
"Traditionally woman have been seen as less bad then men and there has been a denial of female sexuality," she said.
"We see men as perverts and not women as perverts.
"When women commit these offences it isn't because of a sexual interest in children it is for another reason ... they were abused themselves, they were coerced by a man or they have some ongoing psychological issue.
"It is really important that people realise women are capable of committing sexual offences because of a deviant sexual interest and to ignore that ignores the impact upon the victim.
"If you say abuse perpetrated by men is worse than abuse perpetrated by women, you are telling victims that what they experienced isn't as bad.
"You are also telling victims not to report it because it is not as bad."
Dr Nina Burrowes, a psychologist who specialises in the psychology of sex offenders, said society struggled to understand why a woman would commit such crimes.
"I think it challenges our ideas of the role of women in society," she said.
"Women are supposed to be the care givers, women are supposed to be the safe people and when they violate that societal norm, we find that deeply upsetting.
"Society does struggle to accept that women are capable of abusing too and they absolutely are and for very similar reasons to their male counterparts."
Dr Burrowes said there were more male sex offenders than female and due to the low numbers it was hard to draw any conclusions.
"They are rare and the numbers are much lower but if you want to get to the why, the psychology is very similar to what you would expect with their male counterparts," she said.
"There is a category of female sex offender that always has a male co-offender but that doesn't explain all female sex offenders.
"There are so fewer female sex offenders so it is hard to put too much weight on these patterns because there is less of them.
"We shouldn't ever just explain it all away by saying they were manipulated or anything like it. More often or not it is the same reasons as their male counterparts."
But there have been cases where a man has coerced a woman into sexually abusing a child.
Former Lostprophets singer Ian Watkins was jailed in 2013 but as well as committing the crimes himself, he also encouraged a female fan to abuse her child during a webcam chat, as well as enticing another to join him in his abuse.
Ms Kingdon rejected the view that women were sometimes coerced into committing paedophilia to impress a man.
"We rely on that as an excuse for that behaviour. I think it is hard to think that a woman will behave in that way or put a child at risk because it is against the nurturing element," she said.
"In general, with female paedophilia there is a danger in saying or trying to shy away from (the truth).
"If it's a man we are very quick to say that it is for sexual pleasure but as a society we would try and look for excuses to why that behaviour has occurred if it is a woman.
"I think it is dangerous to do that, because if we do, we are ignoring the problem. We would potentially ignore the fact that this does occur and there are women out there who do get pleasure from that.
"With the online world it will come more into the fore."
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