This is the PRIMARY reason for the chain of custody of evidence. Evidence must be controlled every step of the way. If it is not, the evidence can be tampered with and ruled inadmissable. The Chain of Custody will include a detailed record of:
Who obtained the evidence What was the evidence Where and when the evidence was obtained Who secured the evidence Who had control or possession of the evidence
The following answers are incorrect because :
To ensure that no evidence is lost is incorrect as it is not the PRIMARY reason. To ensure that all possible evidence is gathered is also incorrect as it is not the PRIMARY reason. To ensure that incidents were handled with due care and due diligence is also incorrect as it is also not the PRIMARY reason.
The chain of custody is a history that shows how evidence was collected, analyzed, transported, and preserved in order to establish that it is sufficiently trustworthy to be presented as evidence in court. Because electronic evidence can be easily modified, a clearly defined chain of custody demonstrates that the evidence is trustworthy which would make it admissible in court.
Reference : Shon Harris AIO v3 , Chapter-10: Law, Investigation, and Ethics , Page : 727