Final answer:
One of the three basic tasks of a forensic scientist is to preserve evidence, ensuring it remains in its original form and maintaining a proper chain of custody.
Step-by-step explanation:
Failing to document where evidence comes from and/or ensuring that it has not been changed can indeed ruin a case and lead to dismissal by judges. Thus, one of the three basic tasks of a forensic scientist is to preserve evidence. Preservation of evidence involves maintaining its integrity by keeping it in its original form, avoiding contamination, and following rigorous protocols to document the chain of custody. Forensic scientists play a vital role in the analysis of crime scene material, which includes analyzing biological samples such as hair, blood, and DNA, as well as appearing in court to present their findings.