A scientist has completed the Kastle-Meyer test on 3 reddish-brownish stains found in the victim’s car. She then compared them to the positive and negative controls. For the first sample, a pink color appeared 5 minutes after hydrogen peroxide was added. For the 2nd and 3rd samples, a pink color appeared immediately after the hydrogen peroxide was added.

A) What is the result for each? How do you know?

B) Why did the scientist need to run a positive and negative control? What else would she need to do to ensure that all tests and procedures were being done correctly and the results are reliable?

C) After running the Kastle Meyer test, the scientist ran the 3 samples through gel electrophoresis. Bands appeared for sample 3 but there were no bands for sample 1 and 2. Explain what could have happened in each case.