A man accused of raping his daughter for two decades and impregnating her six times was found guilty of 36 rape charges Monday.

A court in the U.K. heard that the unidentified man from South West Wales raped one of his daughters for nearly 20 years and fathered six children with her. He also raped one of the children he had with his daughter. The victim reported the assaults to the police in late 2018. She told the officers that before raping her for the first time, her father told her he only wanted to “teach” her how to have sex. She told the court that she became pregnant with the first child when she was just 14.

The accused admitted to having sex with his daughter since she was 14. He, however, said she “blackmailed him into continuing a sexual relationship.”

“These sickening acts of abuse were carried out by a person that was supposed to protect and care for the victims, but instead he systematically controlled their lives, grooming them for his sexual gratification,” the prosecutor told the court.

Detective Chief Inspector Paul Jones said, “This man has been found guilty of the most serious sexual offences, and it is very difficult to summarize the impact of his crimes upon his victims. I wish to thank the victims in this case for their courage in coming forward. Their bravery and composure throughout this difficult trial has led to the conviction of a very dangerous offender, and I hope from today they can begin to move on and re-build their lives.”

“I want anyone who has suffered abuse to know that if you find the courage to come forward, you will be taken seriously, and police will work tirelessly to bring offenders to justice,” Jones added.

Calling this “one of the worst cases he has heard in 40 years,” Judge Paul Thomas said, “I have been involved in criminal cases as a barrister and as a judge for 40 years. This is in the top three worst cases I have ever had to deal with. I’m used to it, but for you to have to listen to this sort of evidence must have been a difficult experience. I can only thank you for doing your duty.”

The accused was remanded into custody and will be sentenced later this month.

Representational image of a handcuffed man. SERGEI SUPINSKY/AFP/Getty Images