Which type of evidence often requires expert analysis of chemical substances?

Toxicology evidence is particularly significant in forensic science because it deals with the analysis of bodily fluids, tissues, and other samples to identify the presence of drugs, alcohol, poisons, or other chemicals. This type of evidence often requires specialized techniques and knowledge, as toxicologists must use advanced analytical methods such as gas chromatography-mass spectrometry (GC-MS) or liquid chromatography to accurately detect and quantify substances. The complexity of chemical interactions and the necessity to differentiate between various compounds further necessitate expert analysis.

In contrast, other types of evidence, such as biological evidence, often focus more on DNA, blood, or other organic materials which may not require the same depth of chemical analysis unless contamination by drugs or toxins is suspected. Similarly structured evidence often concerns physical similarities and does not primarily relate to chemical substances, and impression evidence, which includes fingerprints and shoe prints, is more about physical characteristics rather than chemical composition. Thus, toxicology evidence stands out due to its reliance on expert chemical analysis.