DP Tool Club 12/CD_ASCQ_12_0294.iso/vrac/leb94jan.zip/94JAN002.TXT

Text File | 1994-01-19 | 16KB | 327 lines

                  FORENSIC IMAGING COMES OF AGE

                               By

                         Gene O'Donnell
                  Visual Information Specialist
                    Special Projects Section


     In 1987, the FBI's Newark, New Jersey, field office
forwarded a then unusual request for forensic assistance to the
Special Projects Section of the FBI Laboratory. Agents asked if
it would be possible to produce age-enhanced photographs of a
longtime fugitive in order to better represent to the public and
to other investigative agencies how the subject might currently
appear. The fugitive, John E. List, had eluded detection since
murdering his entire family 17 years earlier.

     Using newly acquired computer systems, visual information
specialists in the FBI Laboratory prepared an age-enhanced image
of John List and forwarded it to the field office. The office
then publicized the photograph in various national publications.
A woman recognized her neighbor as List (who lived under the
assumed name Robert P. Clark) from the age-enhanced image that
appeared in a supermarket tabloid. The woman dared Clark's wife
to confront her husband with the photograph. Apparently, she
never did.

     Two years later, in 1989, the television show, America's
Most Wanted, featured a plaster bust prepared by a forensic
artist that was based on photographs of List. By this time, List
had moved to Midlothian, Virginia, a suburb of Richmond.
Convinced that Clark was, in fact, John List, his former neighbor
asked her son-in-law to call the FBI and provide investigators
with List's new address. When agents confronted the man, he
denied he was List. But fingerprints from a gun permit
application filed a month before the slayings revealed the truth.
List was arrested and returned to New Jersey, where he was
convicted of murder and sentenced to life in prison.

     The John List case is notable for several reasons, including
List's ability to elude detection for 17 years and the impact of
mass media on his capture. For the FBI Laboratory, the List case
also signaled a new age in computer-assisted forensic imaging.

BACKGROUND

     Traditionally, forensic artists assisted investigators by
producing drawings and airbrushed photographs based on witness
accounts or photographs. Over the years, forensic artists
produced many such images, which assisted in solving numerous
cases. However, advances in computer technology now allow these
same artists to create or alter images much faster, more
accurately, and with many more options than ever before.


     In 1986, the FBI purchased the computer system used for the
age-enhancement of John List. Composed primarily of off-the-shelf
hardware and software, the system allows operators to alter
photographs for investigative purposes by projecting the likeness
of individuals as they might currently appear. By combining the
sophistication of the computer system with the forensic art
skills of the operator, age-enhancement and other imaging can be
achieved with a high degree of accuracy.

     The programmer who developed the system used by the FBI
worked closely with Laboratory personnel in making necessary
modifications to enhance the computer's capabilities. The
user-friendly format allows operators with limited computer
training to make full use of the system. As always, the most
critical element is the forensic art skills of the
operators.

COMPUTER-ASSISTED FORENSIC IMAGING

     The FBI's imaging program is based on a sophisticated photo
compositing and retouching system. The system produces
age-enhanced photographs, merged images (i.e., a human skull
combined with antemortem photographs), and reconstructed facial
images based solely on the skeletal remains. The forensic artist
can also create detailed composite sketches on the system and use
the system to perform other retouching functions.

     In order to produce a desired image, forensic artists must
generate several preliminary images. These initial and
intermediate images, as well as the final product, are collected
together in a folder referred to as a "film."

     A film consists of several images, or "frames," in sequence.
Each frame corresponds to one of the images used to produce the
final product. To ease handling, the artist binds the frames
together in a single film. This also ensures that all materials
necessary to produce the final image can be found in a single
place.

AGE ENHANCEMENT

     The age-enhancement process begins by entering the images
that will be used in an "update" into the computer system.
Forensic artists enter these images into the system in several
different ways.

     In the most common method, the forensic artist uses the
video camera to "grab" or digitize photographs into the system.
This is accomplished by placing a photograph on a copy stand
under an activated video camera to produce an image on the
display monitor. When the photograph has been properly framed,
the camera focused, and the lights adjusted, the image is
"grabbed." The computer then converts the image into digital form
and stores it in its memory. The forensic artist then repeats the
image entry process for each reference image used in the aging
process. When all of the photographs have been entered into the
system, the forensic artist begins creating the aged image.

     The computer displays available commands in a collection of
pop-up menus driven by a fixed menu selection that runs across
the bottom of the screen. The operator selects a category by
pointing to it with a pen-shaped stylus. Once the operator makes
a selection, the list of commands in that category appears in a
pop-up menu. The operator alters the image by selecting different
commands from the various menus and then drawing on the image
using the stylus. Mistakes can be corrected through a variety of
commands.

Child Aging

     When "aging" childhood photographs, forensic artists can
develop highly accurate and detailed enhancements by studying
photographs of the subjects' family members to gauge accurate
facial growth patterns. Since the introduction of the
computer-assisted system, the FBI Laboratory has assisted in
locating several missing persons, based solely or in part, on
this investigative technique.

     To update a child's appearance, the forensic artist enters
photos of the child, as well as one or both parents (or siblings
who resemble the child) into the computer. The operator then
creates grids for each image that "describe" the location of the
facial features in that image. One or more of the missing child's
photographs are "warped" or realigned to bring the features of
that image into alignment with those of another.

     After this process, the images can be composited (or
combined). The result represents the aged image because warping
simulates the growth of the child's face. The percentages of the
images to be composited can also be adjusted to emphasize one
image or another. By adjusting these percentages, as well as the
degree of warping, the artist determines the "age" of the
resulting image. Retouching capabilities allow for various
hairstyles or the removal of blemishes.

     When deciding on what photographs to combine with the
child's image, investigators should look for similarity of
features in the photographs of the relatives taken at
approximately the same age as the missing child. However, in
photographs to be used in the update, relatives must be as close
as possible to the age the child would be currently. The position
of the heads in the photographs of the child and the relatives
must match closely. Facial expressions should also match.
Ideally, photographs should be evenly lit and of high quality.

Adult Aging
     The aging of an adult subject works in a very similar manner
to the updating process for a child. The primary difference lies
in the use of an age template that is combined with the image to
be aged. The artist modifies the template to fit the features of
the image.

     Because cranial growth is complete in adults, the artist
gives special attention to preparing an accurate depiction of the
skin surface, adding necessary creases around the eyes, forehead,
and other appropriate areas. Indications of hair loss in earlier
photos or information from witnesses may lead the artist to
remove hair or make other changes, such as adding a beard or a
scar or adjusting the weight of the face.

     As with the updating of a child's image, any photographs
that are to be combined must be in similar orientations--
preferably head-on shots. Slight deviations from this full-face
angle can be compensated for during the warping process, but some
distortion may result. If the deviation is too great, another
image should be used.

SUPERIMPOSITION

     Forensic laboratories often receive requests for assistance
in cases that require the comparison of an antemortem photograph
with a recovered cranium and mandible (jaw bone). The computer-
assisted system for photographic superimposition offers a highly
effective method to demonstrate consistency (or inconsistency)
between skeletal features and facial photographs.

     First, the antemortem photograph is scanned with a video
camera and then digitized and stored in the computer. The artist
traces key anatomical "landmarks" directly onto a plastic overlay
on the monitor. The image of the photograph is removed from the
monitor, and the image of the cranium and articulated mandible is
oriented manually until the position approximates that of the
individual in the photograph.

     The image of the photograph and the image of the cranium/
mandible are then merged or superimposed to allow detailed
comparison. The artist stores the superimposed images and prints
them on high-resolution printers. Accurate comparison requires
the combined efforts of a skilled forensic artist and an
experienced forensic anthropologist.

FACIAL REPRODUCTIONS

     When investigators find human skeletal remains with few
clues as to their identities, forensic scientists, artists, and
anthropologists often attempt to recreate the images of the
individual from the skeletal remains. In the past,
two-dimensional drawings and three-dimensional reproductions of
the remains--with clay added directly to the cranium to simulate
anatomical features--produced helpful leads for investigators.
     In recent years, facial reproduction has become an
increasingly important tool within forensic anthropology to
identify missing persons. While the technique is of little value
for purposes of positive identification, it can be extremely
useful in presenting an image to the public.

     In computer-assisted facial reproduction, the cranium and
articulated mandible are positioned in what is called the
Frankfort horizontal plane (a scientific articulation of the
cranium and mandible for photographing the cranium) and scanned
with the camera. The artist selects features and adds them to the
captured cranial image. The artist and the anthropologist then
modify the features until a lifelike image conforming to the
proportions of the underlying cranium is produced. In the FBI
Laboratory, facial components are selected from a large database
of handdrawings that depict wide variations in facial features,
complexions, and hairstyles.

COMPOSITE SKETCHES

     For many years, investigators have sought the assistance of
forensic artists in yet another area of forensic imaging-
composite sketching. FBI use of such drawings dates back to 1920;
use in other agencies dates back even further. Television
programs often depict a police composite artist at the bedside of
a victim, quickly sketching a portrait of an unknown assailant.
While real-world forensic artists often produce portrait-style
drawings, these images generally require hours of interviewing,
drawing, and revision.

     The FBI has converted its book of photographs used for
interviewing witnesses for composites into handdrawn images to
use as a database on a computer that will automatically generate
images similar to those that are handdrawn. Once the witness
selects features from the catalog, the composite image appears on
the computer screen in just a few minutes.

     Often, an artist is not even necessary. With practice,
investigators can place the features on the screen and modify the
image as the witness instructs. The system can be loaded into a
laptop computer to further speed up the process by taking it
directly to a crime scene. It can also be accessed via a modem
hookup or put online, with an artist in another city available to
prepare the composite while a witness views and suggests changes.

PUBLICIZING IMAGES

     Investigators should remember that even the most accurate
forensic images are of little value if potential witnesses never
see them. This is especially true of age-enhanced photographs.

     After sending the photographs to Federal, State, and local
law enforcement agencies, investigators should consider
additional ways to publicize the image. The more people who see
the image, the better.

     Generally, programs that spotlight criminals and missing
persons on national or local television and/or in newspapers
yield the best results. One investigator from Oakland,
California, reached out across the United States and Canada with
age-enhanced images of two missing brothers. After exhausting
every lead, the investigator turned to the television program
Unsolved Mysteries.

     On the evening of the broadcast, hundreds of calls poured in
from the Albuquerque, New Mexico, area. Authorities located the
children in a trailer on the outskirts of town, where they lived
with their mother and her new husband--a known drug dealer. The
boys were returned to their father, who had not seen them in
several years. Although the aged images of the boys were very
accurate, the relentless determination of the investigator and
the assistance of the public ultimately solved the case.

     Other methods can be used to publicize an image. Most States
have at least one agency dedicated to the location of missing
children that assists investigators in publicizing such cases.
Wanted and missing person posters often provide a worthwhile
medium. Many printing companies produce posters and flyers
concerning missing children at a reduced rate or at no charge.
Companies offering coupon advertisements featuring missing
children have also proven effective.

THE FUTURE

     New computer-assisted forensic imaging technology looms just
on the horizon. For example, the introduction of three-
dimensional digital skull imaging will give forensic artists the
ability to rotate facial images on screen, allowing for more
movement of facial expression and the addition of detailed facial
features to the image.

     New technology will also enhance superimposition
capabilities. For example, on-screen rotation of cranial images
will allow forensic artists to align antemortem photographs more
accurately.

     These and other improvements will enable forensic artists to
provide new levels of assistance to investigators. Further
computerization of the forensic imaging process promises to
provide law enforcement with enhanced facial identification
capabilities as the 21st century approaches.

CONCLUSION

     For decades, forensic imaging has benefited law enforcement.
Now, computer-assisted programs provide greatly improved
capabilities at a fraction of the time similar imaging once took.
When combined with the communicative power of modern mass media,
the impact of forensic imaging can produce impressive results,
even for cases once deemed hopeless.