Could the crime lab determine if any blood sample came from a male or female?

In most cases, yes.

Sex chromosomes can provide information about a person's sex, and these chromosomes can be found in blood samples. Scientists can use a variety of techniques to analyze sex chromosomes, including:

- Polymerase chain reaction (PCR): This technique is used to amplify specific regions of DNA, including sex chromosomes.

- Short tandem repeat (STR) analysis: This technique is used to analyze specific regions of DNA that are known to vary in length between individuals.

- Next-Generation sequencing (NGS): This technique is used to sequence entire genomes, including sex chromosomes.

By analyzing sex chromosomes, scientists can determine if a blood sample came from a male or female.