Earlier quoted context omitted.
Forensic science in general is an absolute joke. It makes a mockery of the very concept of science. There are a few isolated pockets where the techniques and procedures used are sound, but for the most part the scientific method and rigor are nowhere to be seen.
Care to cite anything about this? From a Biochemist's perspective, when done properly, chemical analysis is extremely accurate and provides a great deal of information.
Forensic science encompasses a broad range of things, including bullet-lead analysis, arson investigation, handwriting analysis, fingerprinting, etc. Various techniques have bordered or even crossed into pseudoscience, others have wildly erratic error bars that are never properly considered. There are so many problems because the entire field does not treat their discipline as scientists do, they are too close to law enforcement for that. Techniques are used for decades before anybody bothers to properly figure out if the technique actually works.