Oksana Grigorieva / Mel GibsonMel Gibson's lawyers claim they have evidence that the explicit, racist tapes Oksana Grigorieva secretly recorded earlier this year were tampered with and edited, which would make them inadmissible in court. To date, five tapes of Gibson screaming threats and obscenities at his ex have been released by RadarOnline.

Arlo E. West, president and CEO of Creative Forensic Services, INC., and one of the nation's leading certified forensic audio and video experts, tells PopEater that the Gibson tapes are altered copies. West, who has listened to all of the tapes, says there are gaps and fading -- which are "red flags" that the recordings have been altered and therefore "cannot be considered accurate." He's also convinced Oksana had professional help to edit the tapes together from a string of conversations.

While there has been speculation about whether or not the tapes are real, RadarOnline is standing by its claims the tapes are authentic. "Numerous top experts who have analyzed tapes for the FBI and CIA, confirm the authenticity of the tapes, as does Oksana's lawyer. Mel can't deny that he said these hateful words, had these brutal arguments and made these threats. The focus remains squarely on these horrible things Mel said and the only question is when will he take accountability for his words and actions?" RadarOnline's David Perel told PopEater in a statement.