Environmental forensic investigations are commonly conducted to determine criminal and civil responsibilities associated with the impact of anthropogenic pollution on human health and/or on the environment. The increasing use of biofuels causes an overall increase on the risk of serious accidents with these compounds, for example, ethanol. The forensic applications for the case of mixtures containing gasoline and ethanol are not well established and the non-inclusion of ethanol effects on the modeling of fuel constituting compounds benzene, toluene, ethylbenzene and xylenes, known as BTEX, can lead to erroneous source age estimation. The calibration of the mathematical model SCBR (Risk Based Corrective Solution) with field data from a controlled release of Brazilian commercial gasoline shows that the aqueous concentration of benzene over time is different whether the ethanol effects are considered or not on biodegradation process of the aromatic compound. These effects, depend mainly on the volume spilled and groundwater velocity, impact differently each contaminated area and influence directly the source age estimation. By considering the effects of ethanol on BTEX transport and fate as well as the specific characteristics of the contaminated site, and the amount of fuel spilled, the SCBR model can be used in litigious disput e as a tool to estimate the source age in forensic issues.