Rug from Porch

[Frigga]

This is what I found:

Body fluids can be detected using alternate light sources. For example, the use of near-ultraviolet light can readily reveal the presence of semen stains. Other body fluids that can be detected include saliva, blood, urine, and vaginal secretions.

 

[sunsetbeach]

I am probably incorrect about this but I thought only blood showed up with luminol & alternative light sources?

Not sure if they were using a black light but I do know a black light will pick up all kinds of stains (cat & dog urine etc). If you think your kitchen counters toilets bathroom counters etc are clean, turn the lights off and use a black light over them and you'll see how dirty they really are. lol. I saw that on some news show a long time ago and since I had two little dogs at the time I checked my carpet and sure enough I could see where they had pee'd.

 

[Frigga]

Sorry Trapshooter- here's the luminol part:

Luminol Shows Investigators the Way

An important tool in detecting biological evidence at a crime scene is luminol (5–amino–2,3–dihydro–1,4–phthalazine-dione). This chemi-luminescent compound gives off blue greenish light when it reacts with metal ions. Iron is stored in the protein called hemoglobin, a component of red blood cells and reacts with luminol. The metallic element acts as a catalyst when it comes in contact with a luminol mixture causing an oxidation reaction.

Normally, Investigators prepare the luminol solution by mixing luminol powder with hydrogen peroxide and other chemicals. Luminol also reacts with other substances like rust or saliva so more tests are needed to positively determine the presence of blood. Since luminol changes compounds it reacts with, original samples of suspicious substances are collected prior to luminol contamination, for further testing to identify the substance.

Read more at Suite101: Crime Scene Chemistry: Tests in Forensic Chemistry for Body Fluids, Fingerprints and Drugs http://forensicscience.suite101.com/article.cfm/crime_scene_chemistry#ixzz0oaJcXVa0

 

[Trapshooter]

Sorry Trapshooter- here's the luminol part:

Luminol Shows Investigators the Way

An important tool in detecting biological evidence at a crime scene is luminol (5–amino–2,3–dihydro–1,4–phthalazine-dione). This chemi-luminescent compound gives off blue greenish light when it reacts with metal ions. Iron is stored in the protein called hemoglobin, a component of red blood cells and reacts with luminol. The metallic element acts as a catalyst when it comes in contact with a luminol mixture causing an oxidation reaction.

Normally, Investigators prepare the luminol solution by mixing luminol powder with hydrogen peroxide and other chemicals. Luminol also reacts with other substances like rust or saliva so more tests are needed to positively determine the presence of blood. Since luminol changes compounds it reacts with, original samples of suspicious substances are collected prior to luminol contamination, for further testing to identify the substance.

Read more at Suite101: Crime Scene Chemistry: Tests in Forensic Chemistry for Body Fluids, Fingerprints and Drugs http://forensicscience.suite101.com/article.cfm/crime_scene_chemistry#ixzz0oaJcXVa0

Thanks Frigga! I'm sorry I was confused on the luminol. Thanks for posting the info!

 

[debbie0604]

Since LE used alternate light source and the porch rug lit up, it would seem that since the A's have yorkies, other areas in the house would have lit up also since alternate light source would hit on areas affected by urine, as yorkies sometimes will have accidents in the house. JMO.. (I used to have a yorkie). Or am I wrong?

IMO I find the porch rug suspicious. But always, it's just my opinion.

 

[gamom]

i believe any biological material lights up under an alternative light source.

I can remember a crime t.v show that had something similar to this, and it ended up being from a dog I do believe dog urine lights up under the special light as well.

Having a yorkshire and two shih tzu's they sometimes pee on the back door mat, if i don't get to the door when they summon me I hope thats not the case with this rug!

I was thinking the same thing. Also, I was thinking that if Caylee is potty training it could be any kind of accident trying to make it from the pool to the potty or car to the potty. I have a toddler along with a dog and I am positive my rug on the front porch would light up.

 

[CuriousTwo]

Having it "light up" would provide LE with an opportunity to test it to determine what the source was. And, if it was determined to be urine, I wonder if, like hair, they could tell whether it came from a person who was alive or deceased?

I was wondering if they'd be able to extract DNA from a urine stain and I'm guessing they can't. From what I've read, extracting DNA from a recent urine sample is very unreliable, so doing it from a dried stain is probably hopeless at this point.