The gel below shows a region of STRs from a DNA sample taken from a crime scene. It also shows the same region of STRs from 4 suspects involved in the case. Which suspect' DNA was found at the crime scene?

• A. Suspect 1.
• B. Suspect 2.
• C. Suspect 3.
• D. Suspect 4.
• E. They are all innocent.

Answer: (B)

Verified step by step guidance

1. Examine the gel electrophoresis image provided. Each lane represents DNA samples from the crime scene and the four suspects.
2. Identify the banding pattern in the 'DNA from crime' lane. Note the number of bands and their positions.
3. Compare the banding pattern of the 'DNA from crime' lane with each suspect's lane. Look for a suspect whose banding pattern matches exactly with the crime scene DNA.
4. Focus on the number of bands and their relative positions in each lane. STRs (Short Tandem Repeats) are unique to individuals, so an exact match in banding pattern indicates a match.
5. Determine which suspect's lane has a banding pattern identical to the 'DNA from crime' lane. This suspect's DNA matches the crime scene DNA.