Luminol

The Alphabet in Crime Fiction - The concept was started by Kerrie at Mysteries in Paradise. This week's letter is the letter L.

Here are the rules: By Friday of each week participants try to write a blog post about crime fiction related to the letter of the week. Your post MUST be related to either the first letter of a book's title, the first letter of an author's first name, or the first letter of the author's surname, or even maybe a crime fiction "topic". But above all, it has to be crime fiction. You could write a review, or a bio of an author, so long as it fits the rules somehow.

LUMINOL

Theory Luminol is used by crime scene investigators to locate traces of blood, even if it has been cleaned or removed. The investigator prepares a solution of luminol and the activator and sprays it throughout the area under investigation. The iron present in any blood in the area catalyzes the chemical reaction that leads to the luminescence revealing the location of the blood. The amount of catalyst necessary for the reaction to occur is very small relative to the amount of luminol, allowing the detection of even trace amounts of blood. The glow lasts for about 30 seconds and is blue. Detecting the glow requires a fairly dark room. Any glow detected may be documented by a long exposure photograph.

Drawbacks

• Luminol chemiluminescence can also be triggered by a number of substances such as copper or copper-containing chemical compounds, and certain bleaches; and, as a result, if a crime scene is thoroughly cleaned with a bleach solution, residual cleaner will cause the entire crime scene to produce the typical blue glow, effectively camouflaging any organic evidence, such as blood. 
• Horseradish sauce, via the enzyme horseradish peroxidase, catalyses the oxidation of luminol, emitting light at 428 nm (blue in the visible spectrum), which may result in a false positive. 
• Luminol will also detect the small amounts of blood present in urine, and it can be distorted if animal blood is present in the room that is being tested. 
•  Luminol reacts with fecal matter, causing the same glow as if it were blood. 
•  Luminol's presence may prevent other tests from being performed on a piece of evidence. However, it has been shown that DNA can be successfully extracted from samples treated with luminol reagent. 

Sources: http://laciudadatomica.blogspot.mx/2011/01/10-luminol.html
http://en.wikipedia.org/wiki/Luminol

Have you mentioned Luminol in your books? Has it solved the crime? 

Also, authors I want to check out that start with the Letter L:

LESLIE CHARTERIS

Leslie Charteris (12 May 1907, Singapore – 15 April 1993), born Leslie Charles Bowyer-Yin, was a half-Chinese, half English author of primarily mystery fiction, as well as a screenwriter.

The Last Hero -This book talks about how the Templar makes the acquaintance of his arch-villain, destroys a dangerous death ray, and thereby saves the world from catastrophe and a second Great War. It was written in 1930.

LYNDA LA PLANTE

Lynda La Plante, CBE (born Lynda J. Titchmarsh on 15 March 1943) is an English author, screenwriter and former actress, best known for writing the Prime Suspect television crime series. La Plante's father was a salesman in Liverpool. She attended RADA and began her career as an actress, mainly on television. As Lynda Marchal, she appeared in several popular series including Z-Cars, The Sweeney, The Professionals and Bergerac.

Trial and Retribution -The murder of a young single mother begins a police enquiry that spirals into a hunt for a serial killer. How much evidence do you need to convict a guilty man; and how much fear can be instilled to make an innocent one plead guilt?

Sources: Wikipedia and Amazon.com
Writing and selling your mystery novel by Ephron
http://www.mentalhelp.net/poc/view_doc.php/type/doc/id/419