FBI Investigates

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.