A German police officer went on trial Friday accused of murdering a willing victim he met on a website for cannibalism fetishists with the aim of making a grisly pornographic home video.

In a macabre case that has captured global attention, prosecutors say the 56-year-old defendant, Detlev Guenzel, killed the man at his home last November, then cut his body into small pieces and buried them in his garden.

"He killed and dismembered him to get sexual stimulation and then later to get sexual stimulation by watching the video he made," chief prosecutor Andreas Feron told the regional court in the eastern city of Dresden.

He could face 15 years in prison if convicted on charges of murder and "disturbing the peace of the dead".

The men came across each other in October 2013 on a website for slaughter and cannibalism fantasies billed as "the #1 site for exotic meat" and boasting more than 3,000 registered members.

A click on a dialogue box allows participants to say if they would like to take their experiences beyond the realm of the imagination.

Investigators say, however, that there is no evidence that the suspect ate any part of the victim.

Guenzel has retracted a confession he made to police in which he said he killed 59-year-old Polish-born Wojciech Stempniewicz by cutting his throat.

His defence team argued that Stempniewicz, who had long expressed a death wish, hanged himself in Guenzel's custom-designed "S&M studio" in his cellar before Guenzel took a knife, then an electrical saw to his body.

- 'A very sheltered childhood' -

Guenzel, a trim man with closely cropped grey hair, entered the courtroom wearing a white hoodie jacket and neat grey trousers and smirked slightly as media photographers took his picture.

He told presiding judge Birgit Wiegand that he would not address the facts of the case but he gave the court a detailed account of his biography.

"I grew up in a beautiful house with my parents and had a very sheltered childhood," said Guenzel, a three-decade veteran of the police force who was raised in the communist east of the country.

"I was the baby of the family and was spoiled by everyone."

Guenzel had been married to his male partner in a civil union for 10 years at the time of the killing but said they divorced earlier this year.

He has two adult children from a previous marriage and said he adopted his partner's daughter, who now lives in Ireland.

"I have close contact with all of them and they have all visited me in prison," he told the court.

Guenzel's partner, neighbours and police colleagues have told investigators they were shocked to learn of his double life.

'Pure horror'

The graphic 50-minute video showing the dismemberment is to be presented during the trial, which is scheduled to last at least until November and hear from around 20 witnesses, including the dead man's estranged wife.

One investigator called the images "pure horror".

But Guenzel's defence attorney Endrik Wilhelm says the recording proves that Stempniewicz committed suicide by hanging himself.

A pathology report indicates he died from asphyxiation and Wilhelm said that his knees were bent while he hung, his mouth taped shut and his hands bound behind his back.

"It is clear he could have extended his legs to touch the floor, in which case he would still be alive," he said.

Stempniewicz -- a business consultant living in the northern city of Hanover -- and Guenzel had extensive contact via email, text message and telephone before finally arranging the fatal date on November 4.

Guenzel picked him up at Dresden's main railway station and drove him back to his house in the mountain town of Hartmannsdorf-Reichenau, which he ran as a bed and breakfast.

Wilhelm expressed fears that the massive media attention had created a bias against his client.

He noted that most reports referred to the infamous case of German cannibal Armin Meiwes, who admitted to killing, mutilating and eating the flesh of a lover in 2001 he had met on the Internet via an advertisement looking for a "slaughter victim".

He was sentenced to life imprisonment in 2006.

The case exposed a murky underworld of violent fetish websites in which volunteers find partners to share dismemberment and cannibalism fantasies and, in extremely rare cases, act them out in real life.