FBI Handbook of Crime Scene Forensics (4 page)

Hair examinations can determine whether hairs are animal or human. Race, body area, method of removal, damage, and alteration (e.g., bleaching or dyeing) can be determined from human-hair analysis. Examinations can associate a hair to a person on the basis of microscopic characteristics in the hair but cannot provide absolute personal identification. Hairs that are associated will be submitted for mitochondrial DNA analysis.

Fiber examinations can identify the type of fiber, such as animal (wool), vegetable (cotton), mineral (glass), and synthetic (manufactured). Questioned fibers can be compared with fibers from the clothing, carpeting, and other textiles of victim(s) and suspect(s). A questioned piece of fabric can be matched physically to known fabric. Fabric composition, construction, and color can be compared, and impressions on and from fabric can be examined. Label searches can determine clothing manufacturer information.

Questions concerning hair and fiber evidence should be directed to 703-632-8449.
Follow the evidence submission directions, including
Requesting Evidence Examinations
and
Packaging and Shipping Evidence
.

• For known hair samples, collect at least 25 hairs from different parts of the head and/or pubic region. Comb and pull out the hairs. Submit hairs in clean paper or an envelope with sealed corners.
  
• When possible, submit the entire garment or textile. Submit fibers in clean paper or an envelope with sealed corners.
  

Examinations of film, negatives, digital images, photographic prints, and video recordings, including surveillance images, involve comparisons of subject(s) or object(s) depicted in questioned images with those in known images. Subject(s) or object(s) also can be compared between multiple questioned images. Subject comparisons include facial comparisons or can be made between like body parts, such as hands or ears. Examples of objects that can be compared include clothing, firearms, and vehicles.

Physical dimensions can be derived from images through the use of geometric formulas or on-site comparison. For on-site comparisons, examiners enter the scene and place a height chart at the location of the subject(s) or object(s) of interest. Examples of photogrammetry include determining the height of a bank robbery subject(s) and the length of the weapon(s) used by the subject(s) depicted in surveillance images.

Photographic evidence—including film, video, and digital images—can be examined to determine whether the image is the result of a composite, an alteration, or a copy.

Examinations of photographic evidence can determine the location, time, and date that an image was taken.

Photographic products, including film and prints, can be dated, and the source can be established by examining manufacturing characteristics. This can establish the time frame during which a photograph was taken.

Cameras, both film and digital, seized as evidence can be compared with images to determine whether a specific camera captured a specific image. Similarly, digital video cameras can be compared with video clips.

Still images can be produced from video clips, enhanced and enlarged, and used in courtroom presentations.

Vehicles depicted in surveillance images can be compared with the National Automotive Image File to determine make and model.

Seized images of child pornography should be searched for known victims by checking with the National Center for Missing and Exploited Children and the Innocent Images National Initiative. The images also can be compared with images in the Child Exploitation and Obscenity Reference File to identify the source of the images. Video clips can be examined to determine if any of the people and scenes depicted in the video clips are also recorded as still images in the reference file. Video clips and still images also can be examined to determine if they depict recordings or images of real people and events or whether they represent computer-generated subjects and events.

Questions concerning image analysis examinations should be directed to 703-985-1393. Questions concerning image analysis evidence should be directed to 703-985-1388
.

Image analysis examinations may not be submitted directly from entities outside the FBI. State, local, or international agency cases must be submitted by the FBI field office servicing the area and must meet one of the following two criteria: 1) the state, local, or international case has a nexus to an ongoing FBI investigation or 2) the FBI division head deems that the case is of enough regional importance to merit the dedication of federal resources to the state, local, or international case. These criteria shall be met with a written statement from the division head (Special Agent in Charge). FBI entities may submit cases directly.

Follow the evidence submission directions, including
Requesting Evidence Examinations
and
Packaging and Shipping Evidence
.

• Write-protect the original media. Never use the Pause operation when viewing original video recordings.
  
• Submit original evidence (e.g., negatives, videotape, CD) whenever possible because it contains the greatest level of detail. If the original media is unavailable, submit first-generation photographic prints, videotapes, or digital files of the evidence, being careful not to introduce further compression.
  
• Process all film prior to submitting. Bank surveillance film should be processed by the bank’s security company according to manufacturer specifications.
  
• When requesting forensic examinations based on video images, queue the original videotape to the approximate time of the pertinent area. State in a communication the date and time of the pertinent area and use the date-time stamp on the images or the counter indicator (set from the beginning of the tape at 000). If prints from the relevant frames are available, submit them for reference.
  
• Arrest or known photographs of suspect(s) for comparison with questioned images must depict the suspect(s) from many angles similar to the questioned images. If a facial comparison is requested, ensure that the face or head of the suspect(s) fills more than half the frame. If questioned images show tattoos or marks, include photographs of the same areas of the body on the known suspect(s).
  
• When taking known photographs for comparison with questioned images, use 35 mm film or digital equivalent (at highest resolution settings to minimize image compression).
  
• Do not mark or cut items submitted for comparison (e.g., clothing or firearms) where they are visible in the questioned images.
  
• Physical items such as clothing and firearms must be submitted to the Laboratory for other examinations such as trace evidence, ballistic, or fingerprint analyses before they are submitted for image comparison.
  
• If photogrammetry is requested, include the dimensions of the scene to the nearest eighth of an inch and include a diagram or print from the relevant images indicating the location of the measurements. Include one diagram or print for every angle used in the scene. Do not touch or move the surveillance cameras.
  
• Submissions for comparison with the Child Exploitation and Obscenity Reference File must be limited to no more than 30 images. Call
  703-985-1393
  for specific instructions.
  
• When submitting such evidence as a videotape or data card, label the outer container “FRAGILE, SENSITIVE ELECTRONIC EQUIPMENT” or “FRAGILE, SENSITIVE AUDIO/VIDEO MEDIA” and “KEEP AWAY FROM MAGNETS OR MAGNETIC FIELDS.”
  
• Address the outer container as follows:
  

  FORENSIC PROGRAM
  BUILDING 27958A
  ENGINEERING RESEARCH FACILITY
  FEDERAL BUREAU OF INVESTIGATION
  QUANTICO VA 22135
  

The Laboratory is the best place to develop latent prints; however, it is sometimes necessary to develop latent prints at crime scenes. Caution should be taken to prevent destroying latent prints. The following measures ensure that crime scene latent prints are protected:

• Photograph latent prints prior to any processing.
  
• Examine all evidence visually and with a laser or an alternate light source before using any other latent print development process.
  
• Photograph latent prints developed with fingerprint powders before lifting them.
  
• Black, gray, or white powder can be applied to a surface with a variety of style of brushes. The color of the powder should contrast with the color of the surface (e.g., black for light surfaces and gray or white for dark surfaces).
  
• Use a short-hair brush or cotton to remove excess powder. Use caution when powdering. Avoid overbrushing latent prints and losing clarity.
  
• Use transparent tape or black-and-white rubber lifts to lift latent prints.
  
• When transparent tape is used, the color of the backing card should contrast with the color of the powders (e.g., white backing card for black powder).
  
• When using latent print development processes, refer to the manufacturer’s instructions and the Material Safety Data Sheets. Use personal protective equipment (e.g., safety glasses, masks, gloves, smocks).
  
• The
  Processing Guide for Developing Latent Prints
  is a comprehensive guide to latent print processes and protocols. Refer to this publication to ensure that proper processes are applied in the recommended order. Following this guide will maximize the potential to develop latent prints and will preserve evidence if other forensic examinations are required. The guide is available at
  http://www.fbi.gov/hq/lab/fsc/backissu/jan2001/lpu.pdf
  . Law enforcement personnel may request the
  Processing Guide for Developing Latent Prints
  in field-manual format by faxing a request on agency letterhead to
  703-632-8374.
  

• Use a tripod and cable release when photographing latent prints.
  
• Use a 35 mm or medium-format camera with a macro lens capable of half-size to full-size reproduction.
  
• Photograph latent prints at each step in the processing sequence before moving to the next process.
  
• Photograph latent prints developed with fingerprint powders before lifting them.
  
• When possible, use ISO 400 film. Set the lens f-stop to the smallest possible aperture while using the camera meter to adjust the camera’s shutter speed to obtain proper exposure.
  
• Take three exposures of each latent print by bracketing:
  
  • Original exposure.
    
  • One-stop underexposed image.
    
  • One-stop overexposed image.
    
• Photograph latent prints individually. This ensures that the target latent print is in focus.
  
• For reference purposes, photograph latent prints close to one another in one frame, if possible.
  
• Fill the frame completely.
  
• Photograph latent prints with an identification label that includes a scale, reference number, date, collector’s initials, and location of the latent prints. The identification label should be placed on the same plane as the latent prints.
  
• Maintain a photographic log that records each shot, reference number, date, collector’s initials, location of prints, and other pertinent information.
  

Questions concerning latent print evidence should be directed to 703-632-8443.
Follow the evidence submission directions, including
Requesting Evidence Examinations
and
Packaging and Shipping Evidence
.

• Stabilize the evidence to avoid movement or friction during shipping.
  
• Place nonporous evidence (e.g., nonabsorbent, hard surfaces) in separate protective coverings such as thick transparent envelopes (glassine), or suspend in a container so that there is minimal surface contact. Friction will destroy latent prints on this type of surface.
  
• Place porous evidence (e.g., paper, cardboard) in separate protective coverings. Friction generally will not destroy latent prints on this type of surface.
  
• Submit known fingerprints and palm prints of everyone who may have handled the evidence, including suspects, victims, those who had legitimate access, and investigative personnel. All fingerprint cards must include pertinent biographical and/or demographic information.
  
• Palm prints should be taken on only one side of a separate card, not on the reverse side of a fingerprint card or on the reverse side of a card that has a recorded impression on the other side.
  
• Fingerprint cards and major-case prints should include, at a minimum, the name of the person printed, the name of the person recording the prints, the date, the case-identification number, and a brief statement of facts relating to the case. The fingerprint card should bear an arrest offense.
  
• The notation “elimination prints” should be included if the person printed is not a suspect.
  
• When known prints are submitted separately from evidence, reference previous communications and case-identifying numbers and other pertinent information.
  

Digital images, including digital photographs, of latent and intentionally recorded prints should include a scale or other measurable item. If a search of the Integrated Automated Fingerprint Identification System (IAFIS) is requested, a scale or other measurable item is mandatory.

Digital images, including digital photographs, must meet the following requirements:

• Documentation of the image source (e.g., window, door frame).
  
• Documentation of the capture device (e.g., flatbed scanner, digital camera).
  
• Documentation indicating the image is an original capture.
  
• File properties for latent images consisting of:
  
  • A file format without compression or with lossless compression (e.g., RAW, TIFF).
    
  • A minimum of 8 bits for grayscale images and 24 bits for color images.
    
  • A resolution that meets or exceeds 1000 pixels per inch (PPI) when calibrated to actual size (1:1).
    
• File properties for intentionally recorded prints consisting of:
  
  • A file format without compression, with lossless compression (e.g., RAW, TIFF), or with Wavelet Scalar Quantization (WSQ) compression saved at a maximum of 15:1.
    
  • A minimum of 8 bits for grayscale images and 24 bits for color images.
    
  • A resolution that meets or exceeds 500 PPI when calibrated to actual size (1:1).
    

Latent prints submitted as facsimiles or photocopies will not be examined in the FBI Laboratory.

Intentionally recorded prints submitted as facsimiles will not be examined in the FBI Laboratory, except when the known prints will be searched against IAFIS in order to obtain FBI file prints.

• Pack each hand or finger in a separate unbreakable, watertight, and airtight container.
  
• Label each container (e.g., “RIGHT HAND,” “RIGHT THUMB,” “RIGHT INDEX”).
  
• Ship the remains in the condition in which they were found (e.g., in water, frozen, dried) by the most expeditious means.
  
• Provide a complete physical description of the deceased, if possible.
  
• Label the outer container “KEEP IN A COOL, DRY PLACE,” “REFRIGERATE ON ARRIVAL,” and “BIOHAZARD.”
  
• All human remains will be returned to the contributor.
  
• Address the outer container as follows:
  

  EVIDENCE CONTROL UNIT
  LABORATORY DIVISION
  FEDERAL BUREAU OF INVESTIGATION
  2501 INVESTIGATION PARKWAY
  QUANTICO VA 22135
  

Legible omple te ten-print fin erprn ar not related to an ongoing Laboratory investigation shoulfi be sent to the FBI’s Criminal Justice Information Services Division
.

• Address the outer container as follows:
  

  CRIMINAL JUSTICE INFORMATION
  SERVICES DIVISION
  FEDERAL BUREAU OF INVESTIGATION
  1000 CUSTER HOLLOW ROAD
  CLARKSBURG WV 26306
  

• Questions on ern n en prn fin erprn cards should be directed to 304-625-2360.