The mother of murdered April Jones has warned "anything can trigger" dangerous sexual predators amid suggestions viewing child abuse images should not always lead to prosecution.
A senior police officer provoked a storm of criticism this week by claiming lower-level offenders should instead be given counselling and rehabilitation for looking at child pornography.
Coral Jones, whose five-year-old daughter April was abducted and murdered by paedophile Mark Bridger in 2012, recalled how the killer had viewed grotesque pictures before his crime.
The Internet Watch Foundation (IWF) also suggested the comments by the National Police Chiefs' Council lead for child protection, Simon Bailey, amounted to telling offenders: "This is a great day to be a paedophile."
Following her killing, April's family started campaigning for "April's Law", calling for sex offenders to remain on the register for life, with a supporting petition garnering more than 125,000 signatures.
In comments released by the IWF, Mrs Jones hit back at the claim abuse images could be "low-level", saying: "You don't know what pictures Bridger was looking at before attacking my daughter.
"He was looking at images hours before he went after April. It doesn't matter what images paedophiles look at. Anything can trigger them off.
"That child could be lucky, or might not be lucky. That family could go through hell. There are men out there looking at photos of children.
"A child could have a photo taken of their abuse and they will have to live with that for the rest of their life. People can be cruel."
The IWF praised the work of Mr Bailey and the internet industry in combating online sexual abuse, but encouraged a "zero-tolerance" approach to offenders.
Chief executive Susie Hargreaves told the Press Association: "I think absolutely we need to make sure we don't give out the wrong message, we don't want to be saying 'this is a great day to be a paedophile because when you look at the images there might not be the ramifications you expected a week ago'.
"What we have to say is we have a zero-tolerance approach to anybody looking at child sexual abuse - it is wrong.
"These are children, these are real children who are abused and whether it's a category C or a category A that is a real child suffering that abuse."
The UK-based internet watchdog has been working to flush child pornography from the internet and said its latest research suggests now just 0.1% of the indecent images are hosted on UK sites.
Mr Bailey, who is also Norfolk chief constable, previously said police should focus on the most dangerous paedophiles with access to children and those looking at the most serious images.
With 400 men a month arrested for viewing child porn, the justice system was unable to cope with the scale of criminal prosecutions which result, he said.
But Ms Hargreaves responded: "Resources is not a reason to let people get away with child sexual abuse."
The officer also added those who were not in direct contact with children and did not pose a threat to children could be dealt with through the use of conditional cautions, requiring them to attend rehabilitation courses and ensuring their names are entered on the sex offenders' register.
The chair of an influential House of Commons committee, Yvette Cooper, said the remarks were of "of great concern" to the cross-party committee.