An enraged father, who disapproved of his daughter's older boyfriend, went to his home and castrated him with a bread knife.
Helmut Seifert, 47, became apoplectic with rage when he heard his 17-year-old daughter was having a relationship with Phillip Genscher, 57.
He went to the Bielefeld town police in Germany, where he lives, but officers said they were powerless to intervene.
'The man then recruited two work colleagues at his factory and then went to the house of the victim,' said police.
'The man was forced to remove his trousers and, fully conscious, he was castrated. The severed testicles were taken away by the perpetrator.'
The man was close to bleeding to death but managed to call police. His life was saved but he remains a eunuch for life.
Seifert pleaded guilty and will be on trial for attempted murder next year. But he has remained silent on who his accomplices were.
He told the police: 'I received a phone call anonymously that my daughter was involved with a guy 40 years older than her. You said you couldn't stop him – so I did.
'I saw it as my duty as a father.'