Latent blood detection with fluorescein

I need help with the reaction between fluorescein and blood in the method of detecting latent blood stains. 


I find it hard to find any literature on this subject.
As far as I am concerned, the fluorescein is reduced into fluorescin in a stock solution with powdered zinc, distilled water and sodium hydroxide pellets.
$\ce{Fe^2+}$ (found in the latent blood) is oxidized into $\ce{Fe^3+}$ with hydrogen peroxide.
When fluorescin is reacting with iron ions in the haemoglobin, it will be oxidized back to fluorescein.


Can anyone help me with this? Maybe even on a molecular level.




Fluorescin(left), a non-fluorescent compound, reacts with iron in residual blood samples to produce highly fluorescent fluorescein(right).


[![Fluorescin and Fluorescein](https://i.stack.imgur.com/Vpd8Y.png)](https://i.stack.imgur.com/Vpd8Y.png)


The reference$\ce{^{[2]}}$ from which the following excerpt is taken describes the chemistry, preparation of reagents, and application to forensics.



> 
> Fluorescin is the oxidized colorless form of fluorescein. Fluorescin reduced with hydrogen peroxide is immediately oxidized to fluorescein in the presence of blood-associated proteins and iron ion found in hemoglobin. Fluorescein fluoresces when viewed using blue light and orange or yellow filters, whereas fluorescin will not fluoresce under the same lighting conditions. 
> 
> 
> 


**Literature Resource**


An excellent starting point to consider for searching for relevant literature is [PubMed.](https://pubmed.ncbi.nlm.nih.gov/)


**References**


1. Image sources - [PubChem](https://pubchem.ncbi.nlm.nih.gov/)
2. [Google Books - Complete Crime Scene Investigation Handbook, Everett Baxter, Jr.](https://books.google.com/books?id=XJi9BwAAQBAJ&pg=PA137&lpg=PA137&dq=fluorescein%20fluorescin%20reduction&source=bl&ots=G-nXq_JZxT&sig=ACfU3U0Mbeq48YfepOlQLb6Obo1wRapOgA&hl=en&sa=X&ved=2ahUKEwisls6lpozpAhXOhXIEHZ4ZDHoQ6AEwEXoECA0QAQ#v=onepage&q=fluorescein%20fluorescin%20reduction&f=false)
3. [Latent-Prints.com - Fluorescein Detection of Latent Bloodstains](http://www.latent-prints.com/fluorescein2.htm)
4. [The Presumptive Reagent Fluorescein for Detection of Dilute Bloodstains and Subsequent STR Typing of Recovered DNA](https://pubmed.ncbi.nlm.nih.gov/11005186/)
5. [A Comparison of the Bluestar and Luminol Effectiveness in Bloodstain Detection](https://pubmed.ncbi.nlm.nih.gov/17249372/)


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