Detectives investigating one of the Netherlands’ most high-profile murder cases of the last 20 years were guilty of ‘tunnel vision’ at the expense of the man who was convicted on appeal, a cold case investigation has found.

A review by three forensic specialists found that the investigating team ignored evidence that could have undermined the case against financial adviser Ernst Louwes, who was found guilty of killing his client, Jacqueline Wittenberg, in Deventer in 1999.

Louwes was initially acquitted of the murder, but in 2004, after two further trials, an appeal court sentenced him to 12 and a half years in jail. He has always protested his innocence.

The case became a cause célèbre following Louwes’s conviction, with opinion pollster Maurice de Hond leading a campaign to clear his name. The media storm was the focus of an award-winning podcast series, De Deventer Mediazaak, broadcast last year.

De Hond claimed in a series of articles, blogs and media appearances that the real killer was Michiel de Jong, a workman who worked in Ms Wittenberg’s home, but was later found guilty of libel and ordered to pay compensation to De Jong and his partner.

Supreme Court

Louwes’s lawyer, Gert-Jan Knoops, has asked the Supreme Court to review the case in the light of the cold case investigation, which was commissioned by Diederik Aben, advocate general at the Supreme Court. It is unusual for the court to ask for a criminal investigation to be reopened after the case has concluded.

The review focused on the records of Louwes’s movements around the time of the murder. In particular his mobile phone signal was picked up by a mast in Deventer shortly beforehand, when Louwes claimed he was 50km away near Hardewijk at the time.

Detectives who retraced the route connected with mobile phone masts up to 108km away, but this evidence was not included in Louwes’s case file.

The review team also noticed ‘discrepancies’ in photographs of the blouse the victim was wearing at the crime scene, in the mortuary and during the autopsy. DNA traces found on the blouse were a crucial part of the evidence used to convict Louwes.