Ninhydrin, and Iodine-Fuming


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.)

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

Hank is also a 2008 Agatha nominee!

Police Department Fingerprint Lab


When working in a laboratory setting, detectives dust for prints under an exhaust hood. Fingerprint powder is extremely messy, like charcoal.

Detectives use light, brushing and swirling motions to apply print powders.

Fingerprinting material – powders, tape, and brushes. Brushes are stored in narrow, plastic tubes seen in the lower right-hand corner of the cabinet above. This helps retain the shape of the brush.

Detectives place the handle of the brush inside the tube first, then give the end of the tube a slight tap on a flat surface, such as a tabletop. The entire brush then gently slides all the way into the tube in a single motion. A trick-of-the-trade.


CynoVac fuming chamber for glue-fuming prints on large, bulky items. Glue-fumed prints develop best inside a vacuum. This device is designed to create a controlled vacuum which also prevents over-fuming. Price tag – $1,000.00


The long, black, tube-like device on the countertop above is another CynoVac Fuming Chamber.  It’s designed for glue-fuming prints on long, narrow items, such as rifles and shotguns. Price tag – $1100.00. A CynoSafe is pictured on the left side of the countertop.

Some of the types of fingerprint powders other than the standard black or white (there are many more):

Chrystal violet – enhances sweat residue

Iodine chrystals – for developing prints on porous material, such as paper

Rhodamine 6g – enhances cyanocrylate-develpoed prints

Fluorescent powder – for multicolored backgrounds.

*As a rule, black powder is normally used on light colored surfaces and white is used for dark ones.

* By the way, I’m guest blogging today over at Suspense Novelist. Stop by if you get a chance. My topic is Writing About Cops – It’s Not That Difficult.

Never correct or rewrite until the whole thing is down. Rewrite in process is usually found to be an excuse for not going on. ~John Steinbeck

Sgt. John Howsden on Body Armor


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.



Latent fingerprints are nearly invisble to the naked eye. They’re left when someone touches an object, leaving behind sweat and oils. Detectives make the print images visible by using powder that clings to the oily ridges of the fingerprint.

All police officers are trained to use basic fingerprinting equipment – brushes, powders, tape, and lifters.



Basic fingerprinting kit. 

Investigators use brushes to apply print powder. The best brushes are made from the feathers of a maribou, a member of the stork family. A second type brush – camel hair – is also an excellent brush. Interestingly, camel hair brushes are not made from the hair of actual camels. Instead they’re made from the hair of small mammels, such as rabbits and squirrels. Synthetic brushes are widely used because they’re less expensive than the other types.


Maribou feather brush

After a print has been developed, the detective uses tape that’s similar to wide packing tape to lift the print from the surface. She then presses the tape and captured fingerprint against a white card creating a permanent piece of evidence.

Another great tool – my personal favorite –  for lifting prints is a hinged fingerprint lifter. The front of the lifter is a small square of tape. The second part of the lifter is a white backing. The print is lifted with the tape which is then pressed tightly against the backing to preserve the fingerprint. Lifters come with pre-printed spaces for the date, time, officers initials, and case numbers.


Hinged fingerprint lifter.

* All photographs courtesy of my friends at Sirchie Finger Print Laboratory

* Notice – The Graveyard Shift is pleased to announce a special guest blogger on Monday 3-3-08. Sgt. John Howsden (ret.), a thirty year veteran police officer, will be discussing body armor (Kevlar vests). Stop by and pick his brain. As usual, we’ll have some cool photographs. One is really cool.

* Fingerprinting will continue next week. Be prepared to take lots of notes.




Crime Scenes: Where Do I Start And When Am I Done?


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.


Crime Scene Investigation


Uniformed officers are normally the first police officers on the scene. It’s up to these front-line cops to take charge, calm the chaos, and make things safe for the arriving investigators. Sometimes, crime scenes are large and complicated; therefore, it may be necessary to set up a command post – a central location for coordinating police activities.

Many police departments use mobile command centers, such as converted motor homes and travel trailers. Some patrol supervisors drive vehicles designed to quickly transform into a fully functional command post.

This Oregon police sergeant drives a marked SUV that also serves as a command post during emergencies and crime scene investigations.

Crime Scene Investigation facts:

Patrol officers often assist police investigators with the recovery and collection of evidence.

Not all crime scene investigators are sworn police officers. Many police departments employ specially trained civilian crime scene investigators/technicians. These crime scene investigators do not:

(As seen on TV)

arrest criminals

interrogate or question suspects

carry weapons

participate in, or conduct autopsies

drive Hummers

All police officers are trained to properly collect and preserve evidence. Sometimes, detectives are unavailable; therefore, uniformed officers assume the duty of investigating the crime.


detective and patrol officer bagging a gun at a crime scene

Ohio police sergeant assists a detective with the collection of a firearm.

Crime scenes may be as small as a single room and they can be as large as the site of the entire area encompassing the collapsed World Trade Center towers.

The police are in charge of crime scenes. Coroners and medical examiners are in charge of the bodies of murder victims.

Next – Crime Scene Evidence


Crime Scene Investigation 2



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.



Most crime-scene investigations begin with a 911 call to police. A communcations officer, or dispatcher, receives the call and obtains as much information about the crime as possible, such as the caller’s name and address, weapons involved, number of victims, and the suspect’s name and description.

The dispatcher relays the information to the next available uniformed patrol officer. Patrol officers are normally the first officers to arrive on the scene of a crime.

The first officer who arrives is normally in charge of a crime scene until she is relieved of that duty by a superior officer or a detective.

Patrol officers must quickly assess a scene and determine if they should call for additional back-up, EMS, detectives, supervisors, medical examiner, crime scene technicians, and other necessary personnel. They also give emergency first aid, if needed.


Patrol officer responds to emergency call.

When a patrol officer approaches a crime scene, he does so with caution. He must be certain there are no hidden dangers, such as a concealed suspect, no dangerous gases or chemicals, downed power lines,  and booby traps. Booby traps are quite common with houses and areas occupied by drug dealers.

Once officers determine that all is safe and that a crime has indeed occurred, they call for investigators. Patrol officers must secure the crime scene and protect evidence by keeping everyone outside until investigators arrive. Patrol officers are also responsible for obtaining the initial information – name, address, phone numbers – from witnesses.

A crime scene is secured until investigators arrive.


Detectives normally take charge of all major investigations.

Tomorrow – Crime Scene Investigation – Part 2.


Traffic stop: check your knowledge


During a traffic stop, officers go through almost every emotion imaginable, from the moment they activate their blue lights until the stop has reached its end. They never know what to expect. Is the driver wanted for a crime? Is he carrying dangerous drugs or other contraband? Is he armed? The list goes on.

Police academy instructors teach recruits how to be safe. They set up mock exercises simulating every possible scenario that officers could encounter once they hit the streets.  New officers are taught to do certain things when making traffic stops. The officer in the picture above has positioned her patrol car on an angle to the roadway. She has her left hand on the trunk of the car. She’s looking ahead at the passing car while keeping the driver in her line of vision. She’s standing a certain way. Actually, it appears that she’s doing everything right. Good for her because she had no idea a photographer was behind her. We were pretty sneaky.

Now it’s time to put the shoe on the other foot.  I’m asking each of you to tell me why the officer has decided to do the things she’s done. Remember, she wants to go home at the end of her shift.