David Copperfield is under the FBI microscope, and now TMZ may know why.

Last week, the FBI raided Copperfield's Las Vegas warehouse and seized digital camera equipment and a hard drive to a computer -- this, after a Seattle woman accused Copperfield of sexually assaulting her in the Bahamas.

Sources now tell TMZ Copperfield designed part of his show around "a system for picking up women." During his show, David goes into the audience and chooses women to come on stage. We're told that if David likes a girl, he'll use code words with assistants like "mama" and "secrecy." The assistants mark the women on a map of the inside of the Hollywood Theater at MGM Grand. After the show, the women are brought backstage -- and that's where the profiling begins.

The women are told that David may use them in his show when he comes to their hometown. They are then photographed with a digital camera, asked questions like, "What is your favorite men's cologne?" and "Where do you like to vacation?" We're told one of those vacation spots mentioned by staff is the Bahamas, where the accuser claims she was assaulted. Copperfield owns a cluster of islands in the Bahamas -- which he bought for $50 million.

This may explain the FBI's interest in David's camera system and hard drive. If the accuser is a woman who was brought on stage, the FBI would be interested in a possible M.O.

Copperfield's attorney re-issued his earlier statement in response to this story: "It is important these allegations be put into perspective. An unidentified woman has made serious allegations against David Copperfield. Although authorities have not revealed her identity to us, we know these allegations are false because David Copperfield has never forced himself on anyone."