A scientist has completed the Kastle-Meyer test on 3 reddish-brownish stains found in a victim's car and then she compares them to the positive and negative controls. The first sample turned a pink color 5 minutes after hydrogen peroxide was added and for the 2nd and 3rd samples a pink color appeared immediately after the hydrogen peroxide was added.
From my understanding, the results for the first sample is that it does not contain the blood sample as it took longer than 30 seconds for it to turn a pink color. Anything after that usually turns pink with the addition of hydrogen peroxide at a later time is due to oxidation. The 2nd and 3rd samples turned pink immediately which means that the indicator phenolphthalein and hydrogen peroxide were able to prove that blood was present. Is my understanding correct?