The
Crime
A
security guard making his hourly rounds at the Smith Federal Building
in Washington, D.C., noticed light coming from the building's
back door. He looked inside and saw a wooden box with a note taped
to the outside: "do not come any closer. This box WILL EXPLODE."
Near the box, the guard noticed a large black flashlight. Realizing
the potential danger of the situation, he carefully retraced his
steps and called for assistance.
Initial
Response
The
Metropolitan Police Bomb Squad responded to the scene. After examining
the area, they concluded that the box and the flashlight were
to be treated as potential explosives devices. They shot a water
cannon at the two items, effectively rendering them safe. The
Bomb Squad contacted the Evidence Response Team (ERT) of the FBI's
Washington Field Office (WFO) after disabling the wooden box and
flashlight. The ERT collected, classified, and packaged the pieces,
while the WFO assigned a Case Agent to lead the investigation.
The
Investigation
The
box and the flashlight were sent to the FBI Laboratory's Explosives
Unit; two examiners were assigned. One examiner determined that
the box contained an explosive; the other determined that the
flashlight had been modified into an explosives device. How
did they do that?
The Case Agent soon learned that the flashlight and the wooden
box were not the only important clues. In the bushes near the
door, investigators found a backpack with papers inside. Ultimately,
the investigation and eyewitness accounts led the Agent to a suspect.
The Agent requested and executed a search warrant for standard
samples of the suspect's blood, handwriting, hair, and paint from
his motorcycle.
Laboratory
Results
While
combing the grounds for additional clues, a tiny piece of metal
was discovered inside the door. The metal was immediately taken
back to the laboratory, where it was sent to the Firearms and
Toolmarks Unit (FTU). The unit compared the piece of metal found
inside the door of the building with a screwdriver that was later
found at the suspect's residence. How
did they do that?
The DNA Unit analyzed blood found on the screwdriver.
It matched the DNA taken from the suspect. How
did they do that?
Witnesses interviewed the night the bomb was
found told the Agent that they saw a man riding his motorcycle
away from the building. Paint chips were recovered next to the
door where the suspect leaned his motorcycle. The Chemistry Unit's
Paints and Polymers sub unit (PPSU) compared these paint chips
with those taken from a part of the motorcycle that was submitted
as evidence to the lab. How
did they do that?
Fingerprints and palm prints were found on
the recovered motorcycle and on the screwdriver. The Latent Fingerprint
Unit compared the prints and determined that they matched the
suspect's fingerprints. How did
they do that?
Hair was also found on the backpack. Trace
Evidence Unit analysis determined that it was a human head hair.
After obtaining a known head hair sample from the suspect, it
was determined that the hair found on the bag was consistent with
having come from the suspect. How
did they do that?
In the backpack, investigators also found a
map and handwritten directions to the building. The directions
were written on a piece of paper that appeared to have been torn
from a notebook. The Questioned Documents Unit compared the handwriting
used on the note with a sample of the suspect's handwriting and
found that they closely resembled one another. How
did they do that?
FBI Agents presented this evidence to prosecutors for court proceedings.