Explosives Unit

The Explosives Unit assigned two examiners to this case. One examiner, a Forensic Chemist, examined the powder that was in the suspected explosive device and determined that it was consistent with smokeless powder, a low explosive. Smokeless powder is commonly used as the propellant in pistol and rifle bullets.

Another examiner in the Explosives Unit, an Explosives and Hazardous Devices Examiner, looked at the remains of the flashlight. This examiner determined that the flashlight had been modified to become an Improvised Explosive Device (IED), also known as a homemade bomb. The IED was constructed using smokeless powder and an electric blasting cap hidden inside the flashlight. The power for the IED was supplied by the batteries inside the flashlight. This type of IED is also called a "booby trap" since it is designed to function when someone picks up the flashlight and unknowingly turns it on.

Firearms and Toolmarks Unit

The Firearms and Toolmarks Unit (FTU) received and handled the evidence related to the screwdriver found in the bag and the piece of metal found at the scene.

The evidence examined by the FTU was first prepared for analysis, by weighing and photographing the screwdriver. In addition to these preliminary examinations and research conducted by technicians and the microscopic analyses performed by examiners, the evidence underwent a variety of testing.

Toolmark examinations of the screwdriver also required an examiner to make casts of impressions left by the tool. A clay dam was created around the toolmarked area (in this case, on the doorjamb) and an epoxy, or plastic casting material, was poured into the area.

The detail obtained with this procedure was so good that once the cast had set and dried, it could be examined and compared microscopically with the broken tip of the screwdriver that was found inside the door of the building. They matched.

Paints and Polymers Sub-Unit

A visual comparison was made between the paint chips from the scene and the paint from the motorcycle. The Paints and Polymers sub-unit (PPSU) of the Chemistry Unit attempted to physically refit the paint chips to the damaged area. This was done in much the same way as a jigsaw puzzle where pieces fit a specific way. A microscope was used to evaluate the minute details of this "physical refit" between the paint chip and the paint on the motorcycle.

If there had not been a "physical refit," the PPSU would have taken a paint sample from the motorcycle part near the area of damage and viewed the samples under a microscope to determine what the paint "looked" like.

But, since the paints were consistent, the PPSU began to examine each layer of the paint from the scene and the motorcycle using various analytical methods. Every type of paint is made up of various components or "ingredients" and two paints that are of similar color may not be of similar chemistry or make-up.

Because no discrepancies were noted between the two paints upon completion of the exams described above (visual, microscopic, instrumental), a positive result was reported. If at any point the paints were inconsistent, examinations would have been discontinued.

Trace Evidence Unit

The Trace Evidence Unit of the FBI Laboratory provided scientific examination of the hairs and fibers found on the bag. When they received the bag as evidence, they took the item into a separate clean room and removed the hairs and fibers found on it. These were then mounted on a glass microscope slide for microscopic examination.

The examiner compared the hairs and fibers collected from the evidence with those collected from the suspect (a head hair sample) and his clothing (fiber samples of each item of clothing that the suspect was wearing). The examination was done using a comparison microscope. A comparison microscope is simply two microscopes joined together that allow the examiner to see the questioned sample (hairs and fibers found on the suspect's bag) and the known sample (known hairs taken from the suspect's head and known fibers taken from the suspect's clothing) at the same time, side by side.

The examiner determined that a head hair found on the bag exhibited the same microscopic characteristics as hairs in the known head hair sample from the suspect. The hair found on the bag is consistent with having come from the suspect.

DNA Analysis Unit

The dried blood that was found at the scene was absorbed onto a clean cloth that had been moistened with distilled water. A portion of the cloth was left unstained as a control. It was then air dried and packed in an envelope.
The DNA Analysis Unit then analyzed the blood sample using various techniques. The results of the analyses were then compared to the blood and saliva obtained from the suspect and a match was made.

Questioned Documents Unit

When the Questioned Documents Unit received the evidence, the examiner assigned to the case began the examination of the paper and the handwriting.

Before beginning the handwriting comparison, the examiner conducted some preliminary experiments. They included examining the paper that bore the map and directions. They paid particular attention to broken paper fibers, which could be used to link it with the notebook from which it was taken. Since the arrangement of paper fibers is random, the relationships/connections between them are unique. As a result, the examiner showed that this sheet was once part of a notebook that came from the suspect's home. Such an examination is termed a "physical match" and can occur on almost any item, including: paper, matches, tape, and anything with perforations.

Before beginning the handwriting/handprinting comparison, it was important for the examiner to determine whether the writing was freely prepared, meaning that it was not distorted (such as block printing or shaky writing). If the examiner had found characteristics of distortion, then the writing might have been a drawing of another's handwriting (called a "simulation"), or a tracing of someone else's writing. The actual comparison was a side-by-side study of the questioned writing (directions) with known writing of the suspect. The examiner found that the handwriting/handprinting on the note was prepared by this individual.

Latent Fingerprint Unit

The Latent Fingerprint Specialist in the Latent Fingerprint Unit (LPU) found a palm print on the motorcycle. A latent print is a print left on an object by the body's natural greases and oils, rather than one taken using printer's ink. Fingerprint powders, chemicals, and even lasers are used to make the latent prints visible on the crime scene evidence. These were then compared to the inked prints of the suspect; they matched.