Final answer:
The most useful sample at a crime scene for identifying a suspect is biological material containing DNA, such as hair, blood, or saliva. Forensic scientists use DNA fingerprinting to compare these samples with those from suspects or victims. DNA evidence is crucial for making connections to the crime scene and is a fundamental tool in forensic analysis.
Step-by-step explanation:
When examining a crime scene, the most useful sample for identifying the person who committed the crime would be any biological material that contains DNA. This could be hair, blood, or saliva found at the scene. DNA is unique to each individual, with the exception of identical twins, making it an ideal tool for forensic identification.
Forensic scientists use DNA fingerprinting techniques to analyze DNA sequences from samples collected. They perform RFLP analysis and polymerase chain reaction (PCR) to amplify and compare the DNA. The sample's unique banding pattern obtained through agarose gel electrophoresis can be matched with those of suspects or victims to establish a connection to the crime scene.
By analyzing the similarities in the sequences, forensic geneticists can determine whether the crime scene sample contains DNA that matches a suspect. This process has become a cornerstone in forensics. Although a detective cannot witness the crime firsthand, the DNA evidence provides a level of certainty about who was present when the crime occurred, similar to how chemists formulate theories based on observable properties in a laboratory.