The man accused of abducting and murdering schoolgirl April Jones had shown an interest in child pornography and child murder cases, a court has heard.
Mark Bridger, 47, is accused of the abduction and murder of April, who went missing from her home in Machynlleth, North Wales, in October 2011.
Bridger admitted he "probably" killed the five-year-old, but said he does not remember what happened to her body.
Traces of blood and burnt bone fragment believed to be from the five-year-old girl's skull were found at the home of Bridger, a jury was told on the first day of trial.
Bridger denies abducting and murdering April and perverting the course of justice by hiding or destroying the body. It has never been found.
Prosecutors at Mold Crown Court said there was a "sexual motive" behind the killing and evidence on his computer revealed that the 47-year-old was interested in child pornography and child murders.
The court heard how Bridger had pictures of April on his computer and had at one time typed "naked young five year old girls" and "nudism five-year-old" into an internet search engine.
On the day April went missing, Bridger is also alleged to have viewed an explicit cartoon depicting rape.
Bridger also had images of murdered Soham schoolgirls Holly Wells and Jessica Chapman.
The jury was shown some of the material on Bridger's laptop, which the prosecution warned was "very unpleasant".
Playing a cruel game
Opening the case for the prosecution, Elwen Evans QC told the jury this evidence may be key to "understanding what he did and why he did what he did".
The court heard how despite an "extensive clean-up operation" traces of April's blood were found at the home of Bridger, as well as a number of knives near a wood-burning stove.
Bridger - an experienced abattoir worker - is accused of playing a "cruel game" by telling police he did not know where the body was.
"The defendant was an experienced slaughterman who knew how to use knives professionally," Evans said.
Bridger claims he does not remember what happened to April's body due to a combination of "drink, panic and adrenalin". He claims he put the schoolgirl in his Land Rover after he accidently ran over her.
Evans told the court: "We can say that April was happy and smiling when she got into the defendant's vehicle because April's best friend saw her abduction take place. She saw the defendant speaking to April, she saw April getting into his Land Rover. She saw the defendant drive April away.
"It's the defendant's case that he admits that he drove her away. He admits that April is dead. He accepts that he killed her or probably killed her.
"He accepts that he must have got rid of her body."
Evans added: "In addition to child pornography and photos of young girls, the defendant also had an interest in child murder and rape cases, for example, images of Holly Wells and Jessica Chapman from the Soham case.
"Why will you need to consider this sort of material?
"You will have to decide whether pretty five-year-old April was abducted and murdered or run over by accident and killed, as the defendant says.
"We say his interest in pornography, young girls, rape and murder cases is all too relevant and you may see it as the key to understanding what he did and why he did what he did."
The search for April was one of the biggest in police history.
The trial is expected to last until June.