There may be other victims out there
Inspector James Holden-White, the senior investigating officer in the case, said: “He is brutal, there is an arrogance about it, that he thinks he can get away with this kind of thing.
“He knows that in the target of heterosexual men, who are a demographic of the population, who are extremely unlikely to think that something like this would ever happen to them in the first place, but even more unlikely to emerge.
“Any victim of sexual offenses will find it very difficult to come forward for various reasons, but for straight men it may be the most unlikely group to come forward or those who will find it most difficult to do so. .
“This, we believe, is exactly why he targeted heterosexual men in this particular case, and it therefore seems entirely possible that he may have offended before and that there may be other victims out there.”
Oxford Crown Court has heard that Da Silva Neto tried to pay off one of his victims, but he was refused and was subsequently reported to police.
Mr Holden-White said: “He is going out, and in the first case he has found someone he knows, exactly where he wants him, in a position of vulnerability where he is capable of administering this drug.
“In the second offense, he went out and targeted someone who was already drunk, and he could get him where he wanted him, give him this drug … could offend him.”
Da Silva Neto will be sentenced later this month.