A method for automated detection of illegal substances smuggled inside internal cavities of a passenger, e.g., as capsules. The method provides for an automated detection of narcotics hidden in a passenger's stomach area using pictures produced by an X-ray scanner. According to an exemplary embodiment, throughput of the scanner is increased by an automated detection algorithm, which takes less time than visual analysis by an operator. The operator is only involved in cases when narcotics are detected. The automated detection method has a consistent precision, because the effects of tiredness of the operator are eliminated. Efficiency and costs of the process are improved, since fewer qualified operators can service several scanners.