[Ramon21]

I have a few questions

When might a latent fingerprint be permanent ?

If iron is the catalyst for tests that detect presence of blood, what compounds might give a false positive test?

Will the test for blood work only for human blood or will it detect animal blood?

What Characteristics must be possessed by the powder with which fingerprints will be dusted..

Please help with any you can

Thanks

[medgen]

If iron is the catalyst for tests that detect presence of blood, what compounds might give a false positive test?

Iron is not the catalyst in these tests, heme is. More specifically, the peroxidase-like activity of heme is measured in these assays. Consequently, anything that contains a peroxidase (e.g. fresh plant extracts) or can oxidize hydrogen peroxide can theoretically produce a false positive. That said, if you use the gold standard, the Kastle-Meyer test, it is functionally specific for blood when red-brown stains are tested in the three-step process.

Will the test for blood work only for human blood or will it detect animal blood?

The chemical tests will detect animal blood. You need an ELIZA-type card assay to specifically identify human blood.