Serial killers have become enormously successful entertainment themes in popular fiction, films, and even an HBO series. These days, the FBI is operating a museum featuring the letters, art and artifacts associated with serial killers, called the Evil Minds Museum.
It is discussed in this FBI Podcast by the FBI Behavioral Sciences Unit.
Unfortunately, the museum is not open to the public and is only intended to be used by criminal investigators, intelligence professionals, and academic researchers. Dr. Lecter could get in, but not you.