Over long period organophosphorus pesticides (OPPs) such as Tusk, Dimex, Dysac, Sacban and Monovip contain Malathion, Dimethoate, Dichlorovos, Chlorpyrifos and Monochrotophos as active chemicals, respectively are used in agriculture to enhance the crops yield. However, these chemicals are extensively used in criminal cases such as suicidal, accidental, and homicidalthroughout the world. Such cases can conveniently be resolved with the help of spectral library as reference/standard to compare with unknown/suspected samples recovered from scene of crime. Te spectral library was generated using ATR-FTIR technique which reliable and non destructive in nature. Tis spectral library has been applied to identify the OPPs in different biological samples and investigate, characterize the OPPs.ATR-FTIR spectroscopic data are, therefore, a prerequisite for their identifcation. Finally, we believe that the use of ATR-FTIR should make it possible to identify all tested OPPs in one single analysis, even in the low ppm concentration range.