Kelly is crime scene Investigator. She is examining a staln that she suspects is

Kelly is crime scene Investigator. She is examining a staln that she suspects is blood. Presumptive tests Indicate blood, so she is choosing which confirmatory test to use. What are the disadvantages of confirmatory tests?
Kelly considers using the Kastle-Mayer test to confirm whether the staln blood; however, she knows that it could be unreliable
because the stain is on a leather boot. Kelly considers using the
test, but she believes the stain may be about 35 years
old, and this test is not as reliable for stains over 20 years.