CHICAGO - A forensic expert testified Thursday at R. Kelly's child pornography trial that a fingernail-sized mark seen on the lower back of the man in the sex tape at the center of the case was not a mole but video distortion. Video analysis expert Charles Palm testified for the defense that the black mark appears — and disappears — because the video has been duplicated so many times.

Jurors last week watched a 4-by-4-foot monitor where freeze frames of the man's back were shown. Just above his waistline was a mark that the prosecution's forensics expert, Grant Fredericks, said appeared to be a mole. He compared the frames with 2002 police photos of Kelly's back, concluding the spots were in the exact same position.

Palm disagreed Thursday.

"I see a black mark but it doesn't appear to be a mole," Palm said.

Kelly, 41, who won a Grammy Award in 1997 for the song "I Believe I Can Fly" and whose biggest hits are raunchy ballads like "Ignition," is charged with child pornography for allegedly videotaping himself having sex with a female who prosecutors say was as young as 13. He has pleaded not guilty and faces up to 15 years in prison if convicted.

Both Kelly and the alleged victim, who is now 23, deny it's them in the video.

Palm disagreed with Fredericks and another prosecution witness who testified that digitally altering the nearly half-hour video — 100,000 frames on the entire footage — would be practically impossible, requiring that someone go through each frame to calibrate everything from shadows to blinks of an eye so that they all move in perfect sync.

Palm testified that a video like the one at the heart of the case could be mocked up in mere months. By way of example, he showed jurors footage of the sex tape that he manipulated. In it, images of the male and female fade in and out against the tape's distinctive log-cabin background.

"I created most of that over a couple of spare hours," he said.

On cross-examination Palm acknowledged that the tape shown by prosecutors during opening statements did not appear to be manipulated, but he said the picture quality was too degraded for him to be sure.

Earlier Thursday, a private investigator for Kelly testified that he believes the prosecution's star witness and her fiance were trying to get money out of the singer when they claimed a publisher had offered them a $300,000 deal for a book about Kelly.

Defense witness Jack Palladino said he took the claim by Lisa Van Allen and her fiance, Yul Brown, as an attempt to extort money in exchange for their silence. Van Allen testified earlier this week that she had multiple three-way sexual encounters with Kelly and the alleged victim in the case.

"I assume they were trying to solicit a bribe," Palladino said of a meeting with Allen and Brown in the Atlanta area earlier this year.

Under cross-examination, Palladino conceded that neither Van Allen nor Brown directly asked for a bribe, but he said their language "was a coded way to get money from my client (Kelly)."

Palladino added he was sure no book deal existed.

Prosecutor Robert Heilingoetter countered that a book deal was a plausible claim and that Palladino had no grounds to conclude the couple were trying to extort money.

Also Thursday, defense attorneys continued working to cast doubt on the testimony of prosecution witnesses who said they recognized the alleged victim on the tape.

Several defense investigators told jurors at least one acquaintance who identified the alleged victim for the prosecution had told them earlier that she wasn't sure the alleged victim was on the recording.

SOurce: AP