It’s the first you’ve mentioned it. It’s not what you say in your book—I’ve just checked.
However, this is another furphy because the "chemical analysis" provided is not what potential readers are told that is in the book.
"Examines recent chemical analysis of the marks and high-definition photos to reveal errors and other anomalies within the forged Khufu cartouche"
Gorlitz claims that he and Erdmann did not take a sample from the Khufu cartouche but from a separate graffiti. [myblog.robertbauval.co.uk]
It appears that a piece of the Khufu cartouche has been removed prior to 2006, most probably for testing, but no results have ever been published likely due to legal ramifications.
Therefore, Creighton's case relies on "evidence" which is not prima facie. He may wave the Case Closed banner, all he likes, but the charade which he is perpetrating upon the public is so transparent, it places him on shaky legal ground.