Google and Microsoft have faced demands to act over the shocking ease with which child killer Mark Bridger used the Internet to fuel his perversion.
Child safety charities demanded that the Internet giants introduce immediate controls to stop paedophiles gaining access to child pornography.
John Carr of the Children's Charities' Coalition on Internet Safety said: "If these images were not available on the Internet then men like Hazell and Bridger might not go on to kill.
"We cannot blame the Internet for these people but it has opened pathways that lead them on to violent pornography and paedophile material."
After five weeks of horrifying evidence at Mold Crown Court in North Wales, the jury of nine women and three men unanimously found Bridger guilty of abduction, murder and perverting the course of justice.
Mr Justice Griffith Williams told him: "You are a pathological and glib liar. There is no doubt in my mind that you are a paedophile who has for some time harboured sexual and morbid fantasies about young girls, storing on your laptop not only images of pre-pubescent and pubescent girls, but foul pornography of the gross sexual abuse of young children."
Despite a huge effort by police and volunteers, April has never been found. Tiny fragments of a child's skull, however, were discovered in Bridger's wood burning stove, alongside a boning knife.
On his Acer laptop, detectives found an incriminating library of vile images. He had found the violent child porn by searching on Google for simple terms, including: "France: British schoolgirl raped and murdered".
Bridger saved photographs of various child murder victims, including ten-year-olds Holly Wells and Jessica Chapman, murdered by paedophile school caretaker Ian Huntley in 2002.
He had also downloaded numerous sadistic cartoons representing "extremely young girls" suffering sexual abuse.
Facebook photographs of local young girls were also found on his laptop, with files specifically dedicated to April's half-sisters aged 13 and 16.
Pictures of April, who had cerebral palsy and was born with a hole in her heart, were accessed just eight days before she was abducted.
Jon Brown of the NSPCC said: "Internet companies make millions and millions of pounds every year.
"Google need to do more in terms of blocking searches for child abuse imagery but they also need to alert the authorities if someone is blatantly doing these searches.
"We are very concerned that the ease with which they can get child abuse images to fuel their fantasies."
A report by the Child Exploitation and Online Protection Centre has identified a link between viewing child porn online and "contact" sexual offences against children.
Scott Rubin, director of communications and public affairs at Google, said: "Google has a zero tolerance policy on child sexual abuse content. When we discover child abuse imagery or are made aware of it, we respond quickly to remove and report it to the appropriate law enforcement authorities."
A spokesman for Microsoft added: "When we are made aware of any illegal content, we remove it from our services, including our search engine and report it to the police."