the PCR test, or polymerase chain reaction test,
isn’t quite as accurate, it takes much less time
to complete--a week at most. The test can be performed
with minute crime scene samples, to, which helps
investigators who have little physical evidence.
The DNA doesn’t have to be recently collected, either;
the PCR test can still be performed even years after--decades
after--the fact, and still be just as accurate.
This is because the PCT method involves copying
the available DNA and analyzing only one specific
gene, oftentimes the gene called HLA DQ alpha. Geneticists
look for certain types of the gene (alleles) to
determine matches. If no match is found, the donor
was not at the crime scene. Matches are not conclusive,
though, because many people may have--and are more
than likely to have--the same alleles as the donor.
Still, juries have convicted suspects based on PCR