SA killer seeks to overturn conviction

Evidence used to help convict a South Australian man of the murder of a teenage girl more than four decades ago was simply wrong, a court has been told.

Frits Van Beelen was jailed for life and spent 17 years in jail for the murder of 15-year-old Deborah Leach, who was found buried in seaweed at Taperoo Beach in Adelaide in 1971.

Released in 1990, Van Beelen is now seeking to challenge his conviction, using new legislation which allows for a fresh appeal provided fresh and compelling evidence has come forward.

In court on Tuesday, defence counsel Kevin Borick led evidence from internal medicine expert Professor Michael Horowitz, who told the court that evidence presented at Van Beelen's trial by forensic pathologist Colin Manock related to the time Ms Leach died was simply wrong.

The time of death was a key factor in Van Beelen's conviction.

Prof Horowitz said narrowing down the time of death to within one hour based on the girl's stomach contents could not be reliably done in the early 1970s.

Mr Borick also told the court that Dr Manock had since been found to be a "liar, incompetent, unprofessional and unethical" in giving evidence over a long period.

But prosecutor Martin Hinton told the court that Dr Manock's evidence had been challenged at the original trial and nothing presented to the appeal court was fresh or compelling.

The court also ruled against admitting transcript from other trials where Dr Manock's work had since been called into question.

The hearing was continuing.