Where seizures of controlled substances or marijuana are made in excess of 10 pounds in connection with any prosecution or investigation under Chapter 7 (§ 18.2-247 et seq.) of Title 18.2, the appropriate law-enforcement agency may retain 10 pounds of the substance randomly selected from the seized substance for representative purposes as evidence and destroy the remainder of the seized substance. Before any destruction is carried out under this section, the law-enforcement agency shall cause the material seized to be photographed with identification case numbers or other means of identification and shall prepare a report identifying the seized material. It shall also notify the accused, or other interested party, if known, or his attorney, at least five days in advance that the photography will take place and that they may be present. Prior to any destruction under this section, the law-enforcement agency shall also notify the accused or other interested party, if known, and his attorney at least seven days prior to the destruction of the time and place the destruction will occur. Any notice required under the provisions of this section shall be by first-class mail to the last known address of the person required to be notified. In addition to the substance retained for representative purposes as evidence, all photographs and records made under this section and properly identified shall be admissible in any court proceeding for any purposes for which the seized substance itself would have been admissible.