(a) Evidence not retained beyond the investigative stage. Section 3600A(c)(4) has no application if items of the sort it describes - e.g., items that must be returned to the rightful owner, or items that are so large that their retention is impracticable - are not kept until the time when a defendant is convicted and sentenced to imprisonment. Investigative agents may take samples from such items during the investigative stage of the case, in accordance with their judgment about what is needed for purposes of DNA testing or other evidentiary use, or may conclude that the nature of the items does not warrant taking such samples, and the items themselves may then be returned to the owners or otherwise disposed of prior to the trial, conviction, or sentencing of any defendant. In such cases, section 3600A is inapplicable, because its evidence preservation requirement does not apply at all until a defendant is sentenced to imprisonment, as noted in § 28.22(b)(1).

(b) Evidence not constituting biological material. It is rarely the case that a bulky item of the sort described in section 3600A(c)(4), or a large part of such an item, constitutes biological evidence as defined in section 3600A(b). If such an item is not biological evidence in the relevant sense, it is outside the scope of section 3600A. For example, the evidence secured in the investigation of a bank robbery may include a stolen car that was used in the getaway, and there may be some item in the car containing biological material that derives from a perpetrator of the crime, such as saliva on a discarded cigarette butt. Even if the vehicle is kept until a defendant is sentenced to imprisonment, section 3600A's preservation requirement would not apply to the vehicle as such, because the vehicle is not biological material. It would be sufficient for compliance with section 3600A to preserve the particular items in the vehicle that contain identified biological material or portions of them that contain the biological material.

(c) Preservation of portions sufficient for DNA testing. If evidence described in section 3600A(c)(4) is not otherwise exempt from the preservation requirement of section 3600A, and section 3600A(c)(4) is relied on in disposing of such evidence, reasonable measures must be taken to preserve portions of the evidence sufficient to permit future DNA testing. For example, considering a stolen car used in a bank robbery, it may be the case that one of the robbers was shot during the getaway and bled all over the interior of the car. In such a case, if the car is kept until a defendant is sentenced to imprisonment for the crime, there would be extensive biological material in the car that would potentially be subject to section 3600A's requirement to preserve biological evidence. Moreover, the biological material in question could not be fully preserved without retaining the whole car or removing and retaining large amounts of matter from the interior of the car. Section 3600A(c)(4) would be relevant in such a case, given that fully retaining the biological evidence is likely to be impracticable or inconsistent with the rightful owner's entitlement to the return of the vehicle. In such a case, section 3600A(c)(4) could be relied on, and its requirements would be satisfied if samples of the blood were preserved sufficient to permit future DNA testing. Preserving such samples would dispense with any need under section 3600A to retain the vehicle itself or larger portions thereof.