A man who stabbed a doctor and her teenage daughter to death could be released after 52 years behind bars after a court ruled he is too old to want sex.

Klaus Braunig – now 78 – was dubbed the ‘Moonlight Murderer’ – after he broke into his victims’ home in the western German city of Mainz, in the state of Rhineland-Palatinate.

Braunig at first confessed to killing the mother and daughter but later withdrew his confessions.

But he was found guilty of the murder of paediatrician Dr Margot Geimer, 49, and her 17-year-old daughter Dorothee and jailed for life aged 26.

Braunig has made 12 applications for parole but each time the District Court and Higher Regional Court in Koblenz have rejected his application.

Now he could be released after Germany’s Federal Constitutional Court agreed that his sex drive may have decreased because of his advanced age.

A spokesperson told local media: “The resolutions will be rescinded and the matter will be referred back to the Koblenz district court for a new decision.”

The authorities are now going to examine if it is possible to put in place “an accompanying and controlling structure through probation conditions.”

In 1991, Braunig was moved to an open prison but was moved back after he was found in possession of pornography, lingerie and adhesive tape.

Braunig was reportedly a known peeping Tom and flasher but there was reportedly controversy over the sentencing at the time because he had a very low IQ of just 75.