The lawyer who defended R. Kelly throughout his 2008 child pornography case is convinced the singer was "guilty as hell".

Ed Genson has told the Chicago Sun-Times the embattled R&B star received anti-libido drugs to help contain his urges after he was acquitted.

"I’ll tell you a secret," he says. "I had him go to a doctor to get shots, libido-killing shots. That’s why he didn’t get arrested for anything else."

And the former criminal defence attorney feels sure the I Believe I Can Fly singer hasn’t done anything "inappropriate" in years.

Genson also told the newspaper he has no regrets about defending Kelly and keeping him out of prison - because he was just doing his job.

The lawyer, who has terminal bile duct cancer, says, "I didn’t facilitate him. He had already done what he’d done.

"I did facilitate him in the sense I kept him out of trouble for 10 years. I was vetting his records. I listened to them, which ones would make a judge mad."

He admits Kelly's 2003 track Ignition tipped him off about the singer's interest in young girls.

"I was riding in the car, listening to the song and said, 'Are you crazy? This is all I need!'" he explains. "It’s a song related to a guy driving around in a car with his girlfriend. It was originally a high school instructor in a class teaching people how to drive a car... I changed the words."

Kelly referenced beating the child pornography rap in a fiery CBS TV interview earlier this week, when he incorrectly told journalist Gayle King, "People are going back to my past... and they are trying to add all of this stuff, now, to that... I beat my case... You can't double jeopardy me like that. It's not fair."

But the outburst and the entire interview reminded Genson his former client is "not a very bright person".

“What he doesn’t understand is this: If you win a case with somebody, they think they’re bulletproof," the former attorney says. "You’re almost better off, sort of, losing. He thinks he can do whatever the hell he wants. He has done everything he can to hurt himself."

Kelly is facing 10 counts of aggravated sexual abuse, including four against minors - allegations he denies.