State of California v. Douglas S. Mouser
County of Stanislaus, Case No. 139818


State of California v. Douglas S. Mouser
County of Stanislaus, Case No. 139818

In this case, a man named Douglas Mouser was tried for the murder of Genna Lyn Gamble, his step-daughter. Her nude body was found along Dry Creek near Waterford, CA on October 14, 1995. She had been strangled to death.

The state theorized, based on the speculations of detectives and a DOJ Profiler, Michael J. Prodan, that Doug Mouser first killed Genna Gamble at their home in Modesto and then drove her body 20-30 minutes away to dispose of it, likely after she had taken a shower (this, they argued, explained her nudity). There was no evidence of a crime at the Gamble residence. And there was no evidence of Doug Mouser's involvement with the crime at all. During the entire five month trial, only one piece of associative physical evidence was offered by the prosecution: a mark on her leg examined by an expert named Gary Robertson (a photogrammatrist). He testified that this mark was identical to the pattern on the seatbelts in Doug Mouser's car, which he argued supported the prosecution's theory.

However, Mr. Robertson was alone in his opinions. Every other forensic expert that testified on this issue concluded that Mr. Robertson's interpretations had no legitimate basis, and/ or the pattern on her leg was consistent with an underwear mark. This included Dr. John Thornton (defense criminalist); John Yoshida (DOJ criminalist, testifying for the prosecution); Dr. Robert Lawrence (forensic pathologist who conducted the autopsy, testifying for the prosecution); and Dr. James R. Williamson (an expert in photogrammetry with a PhD in Engineering, who has trained the FBI in image analysis, testifying for the defense).

Even when the prosecution attempted to have Mr. Roberston's findings validated by the FBI's Image Analysis Unit, they reported in essence that Mr. Roberston had overstated his findings. As part of their report, they explained that Mr. Robertson had not done anything to exclude other sources for the pattern on Genna Gamble's leg. They further reported, in essence, that he did not apparently understand the difference between class evidence and individuating evidence.

It should also be noted that Mr. Robertson did not have a professional CV, and was unable to define the term forensic science when asked to do so by the defense.

On Monday, December 20th, 1999, the jury convicted Douglas Mouser of murdering his 14-year-old stepdaughter. - Article -


"Experience is neither a liability nor an enemy of the truth; it is a valuable commodity, but it should not be used as a mask to deflect legitimate scientific scrutiny, the sort of scrutiny that customarily is leveled at scientific evidence of all sorts. To do so is professionally bankrupt and devoid of scientific legitimacy, and courts would do well to disallow testimony of this sort. Experience ought to be used to enable the expert to remember the when and the how, why, who, and what. Experience should not make the expert less responsible, but rather more responsible for justifying an opinion with defensible scientific facts."

-Thornton, John I., "The General Assumptions And Rationale Of Forensic Identification," for David L. Faigman, David H. Kaye, Michael J. Saks, & Joseph Sanders, Editors, Modern Scientific Evidence: The Law And Science Of Expert Testimony, Volume 2, (St. Paul: West Publishing Co., 1997)


Expert Testimony:

SA Michael J. Prodan (for the prosecution)

Testified to the following:


Dr. John I. Thornton (for the defense)

Testified to the following:


Brent E. Turvey, MS (for the defense)

Testified to the following: