Replies

True, but worth repeating the article for those who focus so strongly on the dna evidence. It's old and not related to the abduction at all. Here's the article:

How many of us are tired of hearing that the scent dogs didn't hit on the inside of the motorhome because scent dissipates quickly? I did some research a little while ago and found this interesting article from the Institute of K9 Forensics. (Interesting site, too.) What's your best guess for how long a scent will remain? The answer is below, and it might surprise you.

RESIDUAL SCENT IN BUILDING
by Adela Morris and Rita Martinez

Abstract
One of the questions we are commonly asked as forensic canine handlers is "How long will scent last in any given situation?" This is a very complicated question, but we want to begin to unravel the secrets. We know some of the elements that will affect residual scent are heat/sun, wind, humidity and rain.
Our first project was conducted in a closed, unused building. Items were placed in different rooms for 5 hours and then removed.
What is Residual Scent?
Residual is defined by Webster's dictionary as - leaving a residue remaining effective for some time.
Within this paper we are using the term in conjunction with decomposing human scent. Residual scent searches are those conducted when no physical form is present. Residual scent is what is left when the decomposing item has been removed. It is something we cannot see and humans cannot necessarily smell.
Introduction
This project began by accident, so was not preplanned as a residual scent research paper. We make no claims to having ruled out all variables, but are using this project to learn what the variables are and how to more effectively set up our next residual scent project.
Our goal in this paper is to look at residual scent in a closed, unused building and see if we can find out how long a trained cadaver / forensic evidence dog can locate the original scent location. All the dogs used in this project ranged from those with some basic training in the finding of cadaver scent to specialized trained dogs in forensic evidence / body recovery. We see this as just the beginning of ongoing residual scent undertakings.
On November 9, 1996 several items were placed in different areas of a building. The building used was built in the 1930's and was used as classrooms up until 1995. It is part of a large developmental hospital that was built before 1900. Most of the furniture is now gone. There is still human clothing around, chairs, desks, shelves with things on them, wardrobes, curtains, and boxes of books and general effects. The facility has been closed down and most of the buildings are scheduled to be demolished.
Room #11 was used as an activity or day room. It is a large open room. The scent sources were blood (3cc) left to dry on the floor and door in the room.
Room #16 is a closet/storage room off room #11. The scent source was blood (approx. 1cc) on paper on the floor.
Room #5 is a large storage room with closets and shelves. The scent source was a soil sample with dried fluids from a gunshot to the head suicide enclosed in a 50ml vented container. The upper window has been open the whole time in this room.
Room #18 is a large living room. Scent sources were; hair mixed with cadaver scent in the fireplace flue, and a very small amount of blood inside a trash can.
Room #9 is a tiled utility area across the hall from a kitchen area. Scent source was hair and blood in a 50ml container placed in the foot of standing ironing board, so the sample was 5 feet off the ground.
Since the original set up date on November 9, 1996, we have returned to the building 4 times: January 8, 1997, April 2, 1997, July 23, 1997 and December 7, 1997. On our visit in April we found that they had removed most of the original furniture and some boxes of trash, so the building had little left in it. Two of the objects (the ironing board and a box of trash), that had held scent sources were now missing.
Results
Each dog participating in this project was able to find most or all of the locations where the decomposing scent articles had been. We saw dogs, which varied, from full alert and pinpointing to general interest in the room or area.
What we have found so far is; residual scent will last 1 year in a building with minimum environmental influence, or human disturbance. Even after the objects where the scent source had been were removed, the dogs were able to locate the rooms, general area, or pinpoint where it had been.
Each time we have worked the problem we have included teams that had not worked the area before. We now have had 16 teams work the residual scent problem. The dogs have ranged from veteran cadaver trained certified teams to 1 year old puppies (who have been training from 8 weeks of age on cadaver and residual scent).
The rest can be read here