15-19 - Evidence Collection, Handling, and Preservation

During a recent Critical Incident Review, it was noted during two recent deputy-involved shootings a firearm was moved prior to the arrival of investigators.  Although there may be times when moving a firearm is necessary for officer safety issues or for preservation of evidence, the following are some general guidelines of proper evidence collection, handling, and preservation for deputy personnel. 

If it can be done so safely, evidence shall be left undisturbed.  Absent exigent circumstances, do not move evidence at a crime scene unless absolutely necessary.  Examples of situations where deputy personnel might find it necessary to move evidence would be the presence of a riotous crowd, evidence lying in the middle of a busy roadway, weather conditions which may destroy possible deoxyribonucleic acid (DNA) evidence, etc. 

There may be times when a weapon used by a suspect poses a potential danger and needs to be moved for officer safety reasons.  A deputy-involved shooting where the suspect with a weapon is struck, or has dropped one relatively close to their person, may still pose a danger.  In those incidents, deputies may need to secure the suspect’s weapon or move it for safety reasons in order to allow a safe scene for paramedics to treat injured parties.  If evidence absolutely must be moved, the handling deputy should consider the following:

• Avoid touching any area where the lab would typically retrieve DNA or fingerprints. 
• Put clean latex gloves on prior to moving evidence.  Do not wear leather gloves to touch evidence.
• Generally, the best area of the firearm to handle would be somewhere away from the grip area, such as the slide of a semi-automatic pistol or the barrel of a revolver.  
• Do NOT attempt to clear or manipulate the firearm.  Potential fingerprint and DNA evidence may be destroyed; there could be evidence on the chambered cartridge or rounds in the magazine, not to mention the inherent danger of handling an unfamiliar crime gun. 
• Every effort should be made to quickly document the evidence by taking a photograph or by making a quick sketch to record the position of the item as it was found at the scene prior to removal.
• Once recorded, move the evidence to a secure area such as the trunk of a patrol vehicle for further processing at a later time.  Once the weapon is removed, do NOT return it to its original location. 
• Avoid placing item in plastic; use only paper products.
• Remember officer safety is the top priority.

With regard to DNA, weather conditions such as rain can wash away potential DNA on a firearm.  In the presence of rain, protect the item in place with a clean cover that will not touch the item (i.e., some type of tenting mechanism).  This should preserve any potential DNA evidence, absent some torrential flood or water collecting that would contaminate the area.      

Other things to remember related to DNA is to never talk while standing over evidence.  DNA testing is very sensitive, and your profile can be picked up from a saliva stain that is the size of a pinhead.  Do not spit chewing tobacco in or around a crime scene for the above reason.  Assume all evidence could have the potential for DNA and fingerprints. 

The following are some additional things to consider:

• Set up a large perimeter. 
• Always think big and scale down as needed. 
• If you accidentally kick a cartridge case, do not try to put it back where it was. 
• Notify handling personnel of what happened and where. 

This Newsletter was authored with the assistance of Homicide Bureau, Scientific Services Bureau, and Weapons Training Unit.

Information regarding the content of this newsletter may be directed to Field Operations Support Services at (323) 890-5411 or email FOSS at foss@lasd.org.

References

Manual of Policy and Procedures (MPP) Sections:

  5-04/010.10 Preservation of Evidence

  5-09/470.05 Homicide and Deputy Involved Shooting Scene Containment

Field Operations Directive 97-16, Handling of Evidence “Chain of Custody”