4 – 18. Physical security a. Once the UPL accepts a complete specimen from the Soldier, the specimen chain of custody begins. This chain of custody must remain continuously and forensically intact until the specimen’s testing is complete at the FTDTL. b. Proper physical security and storage of urine specimens at all levels are essential to ensure the integrity of the DTP. UA specimens will be secured using the minimum security standards for evidence storage as outlined in appendix E. Unused specimen bottles and cups must also be secured (see para 4 – 24).