Child killer Dieter Pfennig loses appeal over murder of Louise Bell

South Australian child killer Dieter Pfennig has lost an appeal over his conviction for the murder of Adelaide schoolgirl Louise Bell more than 30 years ago after questioning the reliability of DNA evidence.

Pfennig was arrested in 2013 when scientists in the Netherlands linked him to the dead girl's pyjama top, which was found folded on a neighbour's lawn not long after she went missing.

In 2016, he was found guilty of her murder but later lodged an appeal against the conviction on the grounds it was unreliable.

It was dismissed in the South Australian Court of Criminal Appeal on Tuesday afternoon, with Chief Justice Chris Kourakis and Justices David Peek and Tim Stanley reaching a unanimous decision after six months of deliberation.

DIETER PFENNIG FOUND GUILTY OF 1983 MURDER OF SOUTH AUSTRALIAN SCHOOLGIRL LOUISE BELL 

Ten-year-old Louise was abducted through her bedroom window in Hackham West in January 1983. Her body has never been found.

Pfennig was convicted of killing another child, 10-year-old Michael Black, in 1989 and he was in jail when he was arrested over Louise's murder.

But Justice Stanley dismissed his line of reasoning as "fanciful" and said there was no possibility the DNA had been innocently transferred.

"I am satisfied ... that the appellant's DNA was deposited on the top in circumstances which implicated him in Louise's abduction and murder," he said.

"I am not persuaded that the (guilty) verdict is unreasonable".

Justice Stanley said the DNA result was supported by circumstantial evidence, citing several instances of Pfennig's incriminating behaviour around the time of the murder.

The pyjama top was found neatly folded by on a neighbour's front lawn and the woman who discovered it also received a phone call from a man who said Louise was with him.

The voice told her to look under a broken brick at a nearby corner, where police found the girl's earrings.

Pfennig suffered from insomnia and liked to walk the streets at night, according to witnesses at his 2016 murder trial. He lived in the same neighbourhood as Louise when she went missing.

The former physics teacher is serving two life sentences - the other for the 1989 abduction and murder of Michael Black. Michael's body has also never been found.