A sadomasochistic serial murderer accidentally electrocuted himself in his prison cell after wrapping a cable around his nipples and genitals before plugging it into a power socket.

Police in Germany said Egidius Schiffer, 62, killed himself while performing the 'autoerotic act' and that there was no reason to suspect foul play or suicide.

Schiffer - known as the 'Aachen Strangler' after he was jailed for murdering five female hitchhikers between 1983 and 1990 - was still hooked up to the live current when his cell was opened on Sunday morning.

Police in Germany said Egidius Schiffer (pictured), 62, killed himself while performing the 'autoerotic act' and that there was no reason to suspect foul play or suicide

Candida Tunkel, a spokeswoman for Bochum prison in northwest Germany, said the murderer had detached the cable from his bedside lamp to pull off the sex act, The Times reported.

A post-mortem revealed the cause of death was heart failure caused by a surge of electricity through his chest.

Schiffer murdered his victims - aged between 15 and 31 - after picking them up in his car as they travelled home from night clubs.

He tied them up and strangled them with rope before burying their bodies in woodland. He raped three of them.

Police caught him 18 years after his last murder when he was arrested in 2007 for stealing scrap metal.

DNA evidence linked him to the murders.

Candida Tunkel, a spokeswoman for Bochum prison (pictured) in northwest Germany, said the murderer had detached the cable from his bedside lamp to pull off the sex act

He was sentenced to life imprisonment in 2008, Bild reported.

Schiffer - who was married and has a son - confessed but later withdrew his statement.

He claimed that he had only wanted to experience the punishment of being in custody because, as a sadomasochist, it excited him.