The use of multiple keratinous matrices (head hair, axillary hair, and toenail clippings) can help narrowing a period of drug exposure: experience with a criminal case involving 25I-NBOMe and 4-MMC.

The objective of this publication is to present the interest of collecting several keratinous specimens in order to document possible drug impairment at the time of the assault, when knowledge solely occurred 7 months after. A subject committed a murder and within minutes after the crime self-inflicted serious wounds. He was charged to the hospital where he slowly recovered. After several weeks, he was sent to prison. During this period, intelligence indicated possible drug impairment at the time of the assault after using 25I-NBOMe and 4-MMC. Head hair (4 cm), axillary hair, and toenails were collected 7 months after the crime. New psychoactive substances were tested in each specimen using LC-MS/MS, which revealed the presence of 25I-NBOMe and 4-MMC in axillary hair (2 and 6 pg/mg) and toenails (1 and 5 pg/mg). However, the perpetrator claimed that the positive findings were due to contamination in prison. Therefore, the head hair was also tested and results returned negative (LOQ at 1 pg/mg), demonstrating absence of contamination during the last 4 months before collection. Combining the window of drug detection in axillary hair (about 4 to 8 months) and the one of toenail clippings (up to 8 months), and excluding drug exposure during the previous 4 months as well as external contamination as the head hair results were negative, allowed us to conclude that the positive findings in axillary hair and toenails are more likely than not consistent with consumption of both 25I-NBOMe and 4-MMC at the time of the crime.