Nice quote mining effort. Especially cutting off the next sentence in the paragraph:
"The forensic scientific method is a modified form of the scientific method that compares anamnestic evidence obtained by investigators with observable physical findings discovered at the crime scene, in the crime laboratory, or in the autopsy suite."
All he is saying is that witness testimony and the analysis of witness testimony should be included in the investigation. This is in addition to the scientific analysis of physical evidence. In fact, he utilizes scientific investigation of the physical evidence to establish the accuracy of the eye-witness testimony.
Now, the author does seem to conclude that without eye witness testimony you can't find the truth about the past. Yet, his only evidence for this are examples of mistaken conclusions about things like Shaken Baby Syndrome. "The Shaken Baby Syndrome is only one example of how a mistaken use of the scientific method for past events can lead to years upon years of mistakes and injustices. Many other examples could be cited, but there is not sufficient space in this paper to do so. We cannot calculate the injustices brought about by confused science. Some injustices in time may be remedied, but unfortunately most will not." The exceptions do not make the rule, however. What about the even more injustices brought about via inaccurate or fraudulent eye-witness testimony? The author mentions them briefly, but then seems to dismiss them. One also wonders what this guy does when there is no eye-witness testimony? Does he simply give up? He wouldn't keep his job long then... would he?
In the end, this guy is basically making the case that eye-witness testimony should be combined with forensic analysis of the crime scene. That is fine, where such testimony is available. He provides NO evidence to support the idea that eye witness testimony is necessary other than some specific cases where the wrong conclusions may have come about in the absence of eye witness testimony. As I said, the exceptions do not make the rule.