Ninhydin is a chemical that reacts with the aminio acids found in fingerprints. When the chemical contacts the amino acids, the combination of the two turns a bright purple color. The coloring is known as Ruhemann’s purple, named after the man who discovered ninhydrin, Siegfried Ruhemann.

Ninhydrin has been around since 1910, but wasn’t officially used for law-enforcement purposes until 1954. Ninhydrin is especially useful for the detection of fingerprints on porous surfaces, such as wood and paper – items where normal print powders can be nearly useless.

Ninhydrin comes in pre-mixed aerosol cans and, in a chrystal form. When using the chrystals, detectives and crime scene investigators must mix the ninhydrin with a carrier, such as acetone – the same chemical that’s found in fingernail polish remover – or alcohol. The mix is then placed in a spray bottle for use.

Ninhydrin chrystals. (Photo – Sirchie Fingerprint Laboratory)

Spraying Ninhydrin on paper to develop suspected prints. (Photo – Evident Crime Scene Products)

Developed print.

Prints developed with Ninhydrin.

* Ninhydrin can cause ink to run, so it’s best to perform all other testing, such as handwriting analysis, before applying the chemical.

Ninhydrin is extremely flammable; therefore, investigators must use caution when using it.

Iodine fuming kit

Iodine fuming is also used for developing prints on porous items, such as paper, cardboard, and raw wood. Iodine fumes react with fat deposits found in fingerprints. When the chemical contacts the fat, it turns the print a brownish color. Iodine evaporates quite rapidly; therefore, developed prints can fade away. Investigators must photograph fingerprints developed with iodine.

 

Fuming with a iodine fuming gun, a device that blows iodine fumes across the taget area.

Prints developed with iodine fumes turn a brownish color.

* * *

Any man who will look into his heart and honestly write what he sees there will find plenty of readers. ~Edgar W. House

(I stole this quote from Jess Ferguson’s blog site. Thanks, Jess.)http://jessyferguson.blogspot.com/

*I was recently interviewed by Emmy Award winner Hank Phillippi Ryan. You can read the interview here:

http://www.jungleredwriters.com/labels/Lee%20Lofland.html

Hank is also a 2008 Agatha nominee!

 

They stink, chafe, and make you look fat, but they also stop bullets, and for cops, that’s a good thing. Bullet-proof vests are made of a fabric called Kevlar, which is five times stronger than steel.

Vests don’t deflect bullets, but catch them; much like a net stretched across the goal posts catches a soccer ball. Although bullets don’t penetrate, they still deliver a mean punch. Depending on the caliber, the distance and angle of the bullet, it’s been compared to being hit with a line-drive baseball traveling at 130 mph. Bruising and broken ribs still occur, but the survival rate is still improving.

Fewer officers are killed due to this great invention, but just as many, if not more, are still being assaulted. In addition to wearing safety equipment, cops practice “officer safety tactics” that go unnoticed by the casual observer. The following tactics soon became second nature to police officers, thus increasing their chances of surviving on the street.

Police officers always keep their gun hand free. They can’t grab their gun if their hand is filled with a ticket book or flashlight.

When knocking on a door, cops stand to the side. Wooden doors don’t stop bullets.

Police officers, like soldiers,  know the difference between cover and concealment. Concealment, such as the door mentioned above, hides them, but doesn’t protect them from bullets. A car or large tree trunk on the other hand hides them and stops bullets; this is called cover.

To protect their backs, cops, like gunslingers of the old west, keep their backs against the wall. Something the late Wild Bill Hickock forgot to do the night he was shot in the back while playing cards.

Officers stand sideways with their gun-side facing away from the suspect. Not only is it harder for a person to grab an officer’s gun, but the officer is less apt to be kicked in the groin.

Fear of death or injury invokes its own sense of humor. Some cops wear emblems or mottos embossed on our vests. One night I found myself laying on a gurney in the emergency room after a major police crash. When the nurse leaned over me and undid my shirt, she saw my red and yellow Superman emblem ironed onto the front of my vest. Without missing a beat she said, “Hit some Kryptonite, did ya?”

Body Armor

Front and rear sections of an officer’s vest. Desgned to be worn under the officer’s uniform. Vests are custom-fitted for each officer.

Front  Kevlar panel with rectangular pouch for steel trauma plate. Front and rear panels are inserted into a protective, canvas-like covering. The cover (in the picture above, the covering is blue) is not made from Kevlar.

Vest worn on outside of officer’s clothing. Usually worn during search warrant service and other high-risk situations. Also worn by SWAT, undercover officers, and plainclothes detectives.

Reflective lettering on the rear of the vest easily identifies the wearer as a police officer. A smaller reflectice patch is sewn to the front of the vest, too.

About Sergeant John Howsden:

John Howsden is a retired police sergeant with over thirty years experience with the Fremont California Police Department. During those thirty years, he served as a detective, SWAT team member, post-trauma counselor, and verbal judo instructor.

Sergeant Howsden was once involved in a shootout with a murderer/robber. The killer escaped during the gun battle and went on to kill four other people before his capture and ending up on San Quentin’s death row. Sgt. Howsden attended the murderer’s execution as a state’s witness.

* Tomorrow we continue our lesson on fingerprinting with a tutorial on Cyanoacrylate fuming and the use of Ninhydrin.

 

Detectives use a variety of means to collect crime scene evidence. When attempting to locate evidence, investigators must be methodical. One way to be certain they’ve combed every inch of a crime scene is to conduct structured, patterned searches, such as spiral or grid searches.

Spiral search patterns are an effective means of locating evidence.

Grid search patterns are especially effective when searching large areas, such as a field or other open land areas. Each grid block is assigned a number or letter. Detectives use those identifiers as reference points when testifying in court. Example: “I located the murder weapon in block number 4.  I also discovered spent bullet casings in block number 3.”

Alternate light sources (ALS) are useful when attempting to locate hard-to-see evidence, such as fingerprints and body fluids. Devices such as Sirchie Fingerprint Laboratory’s Krime Site Imager are invaluable for detecting and capturing fingerprint images. The KS Imager is battery operated and is capable of recording images in bright light or in total darkness.

All too often, fingerprints are destroyed during crime-scene processing (dusting and lifting prints) Using a device such as the KS Imager  allows investigators the opportunity to photograph a perfect image of a fingerprint before attempting dust and lift it.  Therefore, even if the print is marred, detectives will still have perfect image of the print, an image that’s permissible as evidence.

A detective uses a Krime Site Imager to locate and photograph fingerprint evidence.

Some crime scenes, such as labs used for manufacturing methamphetamine, contain hazardous materials, such as flammable and toxic chemicals and fumes. When searching those dangerous crime scenes, investigators must wear protective gear and clothing.

A detective wearing a hazmat suit gathers evidence from a meth lab.

 

 

 

Okay, our alert patrol officers have determined that they do indeed have a crime scene, and they’ve called in the detectives—us. Before we get started with our investigation, let’s be sure we’re all on the same page.

Everyone knows the difference between a murder and a homicide, right? How about the difference between a crime scene and the scene of the crime? You knew they weren’t the same, right?

First of all, let’s talk about homicide. Homicide is the killing of one person by another. A homicide can be ruled legal if the act was committed in self defense or in the defense of another. Even state executions are homicides.

Homicide is the act of one person killing another.

Murder is a homicide, but…

The scene of a crime is the actual location where a crime was committed—where the killer pulled the trigger, or the spot from where the car was stolen.

A crime scene is any location where evidence of a crime can be found. For example, a suspect robs a bank at gunpoint. The bank is the scene of the crime because that’s where the crime took place. It’s also a crime scene because evidence—fingerprints, video evidence, etc.—can be recovered there.

Scene of the crime. The place where the crime took place.

The robber drives three blocks away and tosses his mask and gun into a dumpster. The dumpster and surrounding area are now a crime scene because evidence of the robbery can be recovered from the area.