Question

A woman with long hair is a suspect in a burglary case. at the crime scene, several long hairs were found attached to a broken lock of the safe. the police obtain a warrant and request a sample of 25 to 50 hairs from this woman. they tell the woman it is important that they pull the hairs from her head rather than to merely cut the hairs. the police suspect that the woman was stealing to help support a drug habit.
a. why is it important that the police pull the hairs from her head rather than cut her hair?
b. why is it necessary to obtain 25 to 50 hairs from this woman?
c. the woman denies that she is currently taking drugs and states that she stopped using drugs a year ago. explain how the police can determine if the woman has been off drugs for over one year.
d. suppose the hairs of the woman match the hairs found at the crime scene. why does this not necessarily prove that she was the guilty party?

Answer 1

a. It is important that the hairs are pulled rather than cut as DNA is found in the hair follicle which is located under the scalp. This is where the hair gets it's blood supply. If there are any drugs in the person's system, traces of it will go into the hair shaft from the blood supply by the hair follicle. b. It's necessary because hair doesn't grow constant or consistent and 25 to 50 hairs are needed for an accurate test. This decreases false positive results. c. The hair drug test can go back to about 90 days to see if she has been clean within that time. Beyond that, interviews with family and friends would also be helpful. Phone records would also show if there has been any contact with a dealer. d.This doesn't prove she's guilty because it just places her at the scene and could be circumstantial.