Question

A crime scene is under investigation, but there is no lead as to a potential suspect. DNA evidence is found at the scene and is properly documented and collected by the crime scene technician. It is then handed over to the state forensic lab for analysis. The lab attempts to extract CODIS markers from it but is unable to do so. What are the next steps?

Select one or more:
a. There are no next steps - if CODIS markers can't be successfully extracted from the DNA, it means it will be impossible to extract other kinds of DNA from the evidence sample as well.
b. Y-STRs give information about the maternal lineage, and this would be a good option for narrowing down the investigation.
c. Mitochondrial DNA is more abundant than the nuclear DNA that CODIS markers come from, so it would be a good option.
d. EVCs, namely hair and eye color predictions, would be good for this case because they can help narrow down what the suspect looked like. Just remember that the science is still new, and the accuracy of the predictions varies depending on the hair color or eye color.

Answer 1

If CODIS markers can't be extracted, alternative forensic techniques like analyzing mitochondrial DNA can be used to examine maternal lineage, and estimating visual characteristics can help profile the suspect. Mitochondrial DNA (mtDNA) is abundant and useful when nuclear DNA is limited. Estimative visual characteristics (EVCs), like hair and eye color predictions, can also offer investigative leads.

Step-by-step explanation:

When a crime scene is under investigation and CODIS markers cannot be extracted from DNA evidence, forensic scientists have several alternative steps to consider. Although answer 'a' suggests there are no next steps, this is incorrect. Instead, forensic techniques allow for other types of DNA analysis even when CODIS markers are not retrieved.

For instance, answer 'c' is viable because mitochondrial DNA (mtDNA) is indeed more abundant and can be analyzed even when nuclear DNA is degraded or exists in very small quantities. Mitochondrial DNA can provide valuable genetic information about the maternal lineage because it is passed from mother to offspring, so while answer 'b' is incorrect in stating that Y-STRs give maternal lineage information, mtDNA can serve that purpose.

Regarding answer 'd', estimative visual characteristics (EVCs), such as predicting hair and eye color, might help in narrowing down suspect characteristics. While EVCs can provide investigative leads, their predictions should be used cautiously due to varying degrees of accuracy. Thus, options 'c' and 'd' suggest reasonable next steps in the investigation process.