Defense attorneys in the R. Kelly trial took a blow yesterday as a forensic expert pointed out a mark on the back of the man in the sex tape, which may account for Kelly's mole.

It was Kelly's defense team that originally introduced the mole in their opening statements last week; arguing that the man on the tape did not have one and therefore it was not their client.

According to the AP, today in court, video forensics expert Grant Fredericks analyzed several frozen frames of the sex tape which revealed a dark mark on the man's back. Fredericks compared the still frames to a photo taken of Kelly's back after his arrest in 2002, where a dark fingernail sized mole is evident.

"There is a mark on the man's back in the exact same position," he said.

The defense countered Fredericks' testimony by suggesting that the back mark in the video is not in the same place as Kelly's mole. Defense attorney, Ed Genson also argued that at one point in the tape, a spot faded in and out of view thus suggesting the tape itself has a technical problem.

Earlier in today's testimony, an FBI forensic expert testified that the male and female participants in the tape were neither computer-generated nor altered.

Instead George Skaluba said the video appears to show "real people in a real environment" and if someone sought to create digital images, it could be costly and timely-taking up to years to do.

Skaluba also testified he could not state with certainty whether it is Kelly or a look-a-like on the tape and that the tape in question is a copy several times removed from the original.

The multi-Grammy award winning R&B singer faces 14 counts of videotaping, producing, or soliciting child pornography. He pled innocent to all charges and if convicted could face up to 15 years in prison.