Luiz Inacio Da Silva Neto, 35, has been found guilty of drugging and assaulting two men in a luxury cottage in the Oxfordshire countryside.
He used the date-rape drug GHB on the two men in separate incidents last year, before going on to rape and sexually assault them.
During the trial, one of the men described how he was with Da Silva Neto at the property in November 2021 when they'd both been drinking.
He told how he'd started to feel tired and lost consciousness. Later, the victim awoke to find Da Silva Neto sexually assaulting him.
In a media interview following the conclusion of the trial, the man, known as "Mark", has spoken publicly for the first time about how the assault has affected him. His real identity has been kept secret for legal reasons.
Luiz Da Silva Neto
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He said: "Basically, he drugged me and he used me. It knocked me out almost instantly. I felt like I needed to lay down.
"I could barely stand on my feet. I was really tired, feeling like I needed to lay down. I know my limits but that's something that was out of my control. I woke up in the middle of the night as well. That's how I saw what he was doing."
"Mark" described how the trauma of the assault had completely changed his life.
He added: "I feel more anxious. I see a counselor and psychologists and it's not easy. Sometimes I have panic attacks. I don't trust people in the same way. I was diagnosed with PTSD. I feel like it's eating me up inside. And I have some anger as well.
"For me, this is the worst experience I've ever lived through. I'm heterosexual. I'm Catholic. I'm religious. This is something that I just need to digest.
"The first couple of months were nerve-wracking . Even now I often can't sleep. I lose my vision and my hearing and need to lie in cold water to try to calm myself down. I just can't deal with it.
"The only thing that I do is try to go to work. I'm not really comfortable socialising."
Now that Da Silva Neto has been found guilty of the assaults, "Mark" says he feels he needs to encourage victims of similar crimes to speak up.
He said: "I feel it's my duty to come forward because these type of people are dangerous to society. Da Silva Neto should be in prison. That's where he belongs. You can't ruin someone's life.
"You need to go to the police because otherwise you never know, someone will die or someone else's life will be ruined. You need to be honest and tell them everything you know. So we have to protect each other as much as we can. You have to talk to someone about it because it's going be there in your head for the rest of your life."
Thames Valley police say they are ready to assist anyone who believes they may have been a victim of Da Silva Neto.
Detectives say anyone who comes forward will be treated with utmost sensitivity and their identity protected.
