Forensic Art 101
Forensic art is any art that aids in the apprehension or conviction of a criminal offender, or aids in the identification of unknown deceased persons. It is primarily used to present visual information to aid law enforcement in focusing on a suspect's appearance through a witness' description. There are four categories of forensic art including:
- Composite Imagery: Graphic images composed of individually described characteristics of the human face (may also include full body drawings or objects). This category includes images drawn by hand, computer generated images, and/or "identi-KIT" composites.
- Image Modification/Identification: Methods of manipulation, enhancement and comparison, as well as the categorization of photographic images. This includes age progression and fugitive update drawings.
- Demonstrative Evidence: Visual information used for court purposes (trial displays); can be computer generated or sketched by hand.
- Reconstructive/Postmortem Drawings: Methods of identifying human remains in various conditions of decomposition. These include 2-Dimensional and 3-Dimensional facial reconstructions from the skull, as well as sketches and computer generated images.
Most often, a forensic artist is called upon to interview a victim or witness about the description of a suspect from a crime in which there are no other leads. The artist interviews the victim/witness on the various features of the face, documents these features, and creates a two dimensional likeness of the suspect involved in the crime. The composite image can also include objects such as tattoos, clothing, vehicles and jewelry to aid in the investigation. The law enforcement agency then works with the media and other agencies to circulate the composite image to the general public to generate tips as to the identity of this suspect. The composite sketch is often an important tool in the investigation.
Forensic artists may also be called upon to assist with a post mortem drawing or facial reconstruction from a skull. This is done when human remains are recovered but investigators have been unable to identify the body. The forensic artist's image can assist investigators in searching missing persons databases. The identification can them be positively made by DNA or dental comparisons.
Based on the condition of the remains, the forensic artist must first decide whether to do a postmortem drawing from the morgue photos, or a two or three-dimensional reconstruction of the face from the skull. The postmortem drawing would be done if there was enough of the soft tissue still left on the skull. In most cases where the body is badly decomposed, a facial reconstruction from the actual skull would have to be done.
Step 1: This is the technical phase of the reconstruction. Vinyl eraser strips are cut to the exact length (in millimeters) according to the tissue depth date chart appropriate for the individual. The tissue depth data chart is compiled from a study on the tissue depth of cadavers done by Rhine and Campbell in 1980. The study took into consideration the thickness of muscle, fatty tissue and connective tissue, as well as skin thickness at a particular morphological landmark on the skull. The tables are prepared for Native Americans and persons of Asian descent, African-Americans or persons of African-derived heritage, and American Caucasoid, or persons of European descent. The tables are further divided by slender, normal or obese groupings, as well as by the sex of the individual.
The tissue depth markers are then glued to the skull at the appropriate anthropological landmarks using a cement glue, which is later removed with acetone. The skull is then photographed, taking care that it is set in the Frankfort Horizontal position (attained by placing the bottom of the eye-orbit horizontal to the top of the external auditory meatus, or bony ear hole) so that there is no perspective distortion. The photograph is then printed in one-to-one prints or life size enlargements.
Step 2: A piece of opaque paper is placed over the print of the skull and the artistic phase begins. This deals with the development of the individual features upon the face. The tissue depth markers act as a guide to the contours of the face. A careful study of the muscle attachment sites on the skull and the subtle asymmetries of the face should be made while creating the drawing. The skull is used as a template for the sketch drawn upon it. The position of the eye-orbits, nasal aperture and position of the teeth create perfect and pre-determined proportion in the finalized drawing.
Step 3: The final drawing rendered from the photograph of the skull can then be released to the media and police agencies for the identification of the victim.
Michigan State Police Forensic Artists are specifically trained in all of the above disciplines. They are able to assist all law enforcement agencies on a 24-hour basis.
For information regarding the topic of forensic art, please contact the MSP Forensic Art Coordinator at MSP-FAU@michigan.gov.