Explanation Documenting the collection and requiring a sign-off when possession changes are essential steps for maintaining chain of custody during an investigation. Chain of custody is the process of documenting and preserving the integrity and authenticity of evidence from the time it is collected until it is presented in court. Documenting the collection involves recording information such as date, time, location, description, serial number, etc., of the evidence. Requiring a sign-off when possession changes involves obtaining signatures from every person who handles or transfers the evidence.