Louise Bell went to bed with her window cracked open. By morning, she was missing.

This story depicts violence against children.

It was about 8.30pm when Louise Bell and her little sister Rachel said goodnight to their parents and climbed into their beds in the small front room of the family's Adelaide home. 

It was a hot January night in 1983, so the window was cracked open just a little to let some fresh air in. 

At 6am the next morning, their mum popped her head in to check on her girls. Rachel was still sleeping, but 10-year-old Louise's bed was empty.

After checking the house, Diane roused her husband and together they spotted something sinister in the sister's room that made them immediately call police. The flyscreen in the window above Louise's bed had been cut from the corner creating a hole. It was flapping in the breeze.

Louise and Rachel Bell's bedroom. Image: SA Police.

Police were quick to mobilise a search party, but after six hours and 2,500 door knocks they found nothing. 

The disappearance of Louise in the middle of the night from a normal, suburban Australian neighbourhood left the community shocked. 

As ABC reporter Candice Prosser told Mamamia's True Crime Conversations, "This was something that you just didn't think could happen. This little girl went to sleep next to her sister in their family home and the next morning she was gone, somehow taken from her own bed. It was just inconceivable that a child could go missing in this way and there'd be no trace."

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Two weeks after Louise's disappearance a local woman received an anonymous call from a man with a European accent. 

He claimed Louise was still alive and was "happy" and "didn't want to go home," but that she was unwell. He mocked the police investigation and then directed the woman to a broken brick on the corner of a nearby road where he claimed to have left the little girl's earrings. 

Police found Louise's gold hoops at the location just four minutes drive from the Bell home, but police were unable to track the caller. 

Two weeks after that, the same woman who received the anonymous call found the yellow pyjama top Louise had been wearing the night she vanished on her front lawn. It had been torn and was dirty and sodden.

Later that year, police turned their attention to Raymond John Geesing based on some information from prison informants who claimed he confessed to them while in jail for other crimes.

He was sentenced to life imprisonment for the murder and abduction of Louise, but the conviction was overturned 17 months later when one of the key witnesses changed his story. Geesing was later jailed again for sexually abusing two sisters in the 90s.

By 1989 police did have their eyes on another potential suspect for Louise Bell's murder. High school maths and science teacher Dieter Pfennig was found guilty that year of murdering a 10-year-old boy, and sexually assaulting a 13-year-old. His daughter played basketball with Louise, he lived near the Bell home and had a German accent (which fit the description given of the anonymous caller), but police didn't have any real evidence to link him to her abduction. 

Several decades later, police started to review the cold case and in 2011 they sent some samples off Louise's pyjama top to the Forensic Science Centre in South Australia. It came back with a probability match that didn't exclude Pfennig.

They then sent the samples over to a very advanced DNA testing laboratory in the Netherlands and they were able to match the samples to Pfennig with a probability of one in a billion. 

On November 19, 2013, Pfennig was charged with the murder of Louise Bell based on the new DNA evidence. 

Pfennig has always maintained his innocence. Post continues after video.

His trial went ahead in 2015, and Prosser, who covered it for the ABC told True Crime Conversations, "It was remarkable for so many reasons.

"I've always remembered this case, I don't think I'll ever forget it. You just got the feeling that it was such high stakes that after so long without answers this was finally the chance for the wheels of justice to start turning in this case." 

Pfennig pleaded not guilty and was tried by judge-alone. The prosecutor painted the picture that he'd spent years obsessed with revisiting and talking about the crime. He'd bring it up to his class while teaching, a pastor and a fellow inmate claimed he confessed to killing Louise, and a taxi driver gave evidence that he drove Pfennig to the Bell family home where he watched him stand outside and smoke a cigarette. 

But it was the undeniable DNA evidence that ultimately helped the judge convict Pfennig in 2016 and sentence him to 35 years without parole. Combined with his previous convictions, Pfennig's total minimum prison time is 60 years. He will be 103 when he's eligible for release.

As Prosser explained, "Even in the judgment nearly 40 years later, the judge remarked on the fact that it just created so much publicity and anxiety in the community, The South Australian community was just so shocked by what had happened. It was just so hard to fathom."

The judge did give Pfennig the chance to reveal the location of Louise's body prior to sentencing, but he refused. It remains one of many unanswered questions in this case, including how he abducted her in the first place. 

Louise Bell was 10 when she was abducted from her bedroom. Image: SA Police.

Given her sister sleeping a metre away and her parents a room away were undisturbed, the judge said it was likely Louise was enticed - not snatched - from her bed. 

Pfennig was her friend's father. He was a local teacher. He was a respected member of her community. 

"There was no other explanation as to how Louise could have been abducted in those circumstances without anyone knowing," said Prosser.

"There are many aspects of the case that I don't think we'll ever know the answers to. When Louise was taken? How she was murdered? When she was murdered?

"But at the end of the day, the judge found that he was satisfied beyond reasonable doubt that it was fitting, and he didn't need to answer those specific questions in order to make his finding."

As Justice Micheal David told Pfennig during his sentencing, his was "the most evil of crimes and it was in no way ameliorated by the passage of time.

"The shock and anxiety that your offence caused the South Australian community cannot be compared to the distress that must have been suffered by the parents and family of Louise Bell.

"The effect of my sentence will be that you most certainly spend the rest of your days in jail."

Feature image: SA Police.