Police Scent Evidence

Scent is evidence, and should be properly collected and preserved, like all other evidence at a crime scene.

When scent material is to be collected at a crime scene, certain operational procedures must be considered and maintained so the integrity of the scent is

What is scent material?
It can be any item which has been worn, handled or in contact with the subject. This could include clothing, personal items (wallet, keycase ,etc. ),

In order that the individuals scent be preserved without contamination, it is important that the items be properly handled, protected and preserved. In criminal cases, it is important to maintain the chain of custody, especially when the dog has made a positive identification which will be used in court

Whenever possible, let the dog handler select the scent material he/she desires upon arrival at the scene. This helps prevent contamination of the article.

If scent material is not available at the scene and is to be selected and transported by another person(s), the following techniques will help prevent contamination of the article.

DO NOT TOUCH. No one should come in physical contact with the item. It should be collected wearing clean rubber gloves and the item should be picked up by using a coat hanger, etc.

PLACE THE ITEM in a clean clear plastic (zip-lock) or paper bag, properly sealed, labeled and stored for future use. Do not use green, black or white garbage bags to collect or store scent articles, they are chemically treated to kill/control odors. (Note: Paper bags may allow scent material to be contaminated.

WHEN USING A FOOT PRINT, protect it from being walked on and attempt to keep people out of the immediate area.

WHEN USING A CAR SEAT, keep everyone out of the car. Normally, the dog will react to the last scent on the seat covering. If an Officer has entered the car, the Officer must remain on the scene until the dog team has arrived and his scent has been eliminated by the dog.

A properly preserved, uncontaminated scent article can be utilized over a period of time. The best way to protect the item is to seal it immediately after use and preserve the item in a freezer if possible. Experiments have been conducted using items kept for months, with success.

In criminal investigations, it is important to note exactly what is used as a scent article, where it was obtained, who handled the article, how it was packaged, and where the item was stored prior to court exhibit.

Proper scent collection / preservation can save lives, it can also assist in solving crimes.

Scent is the unique smell each person has. It is like a fingerprint, no two people are the same. The dog has the olfactory sensitivity to distinguish between people. This ability is what allows us to follow a person through a crowded arena or across a parking lot.

As the first officer on a crime scene, or that of a missing person, you have the opportunity, really the obligation, to preserve all evidence at the scene.This includes scent evidence.

If a trailing dog is called for, a few simple procedures will help make the outcome successful. Lack of knowledge at the scene, can make the K9's job more difficult than it has to be.

CALL AT ONCE, not as a last resort. Time is of the utmost importance.(i.e.,Suspect last seen on foot, eastbound, no vehicle seen, or child playing in front yard and now cannot be found). THIS IS THE TIME TO START A TRAILING UNIT. The unit can always be cancelled, even enroute, if subject is found.

DO NOT let officers, or onlookers, wait or stand near the scene and contaminate the area with scent, or destroy footprints, or evidence possibly dropped by the subject.

TAKE CHARGE OF THE SCENE. First cruiser on location, or rank in accordance to department policy. If criminal, close off the escape route and keep roving patrols in a radius in accordance to the time element. A man has less chance to run any distance if he has to hide.

DO NOT let any vehicle come straight to the scene. Turn off all vehicles in the area. EXHAUST FUMES KILL SCENT.

HAVE ALL KNOWN information ready for the handler and dog. (i.e., Foot-wear, clothing description, physical description of subject, point last seen, weapon, if any).

IF VEHICLE INVOLVED, do not remove it from the scene until after K-9 Unit has arrived and cleared removal of vehicle. If engine running, reach in (DO NOTget in vehicle) turn ignition off and remove the key. Close door and keep everyone away from vehicle.

HAVE AN OFFICER who is familiar with the area available to assist the handler.

Due to the deep concentration between the handler and the dog, which has to be undistracted so as not to miss-read the dogs behavior, a back-up Officer on foot should not try to influence the handler.

IF THE PERSON is located by others while the dog is still trailing, hold until the dog can identify. (THIS IS VERY IMPORTANT.)