Searching for Evidence

Investigators need to conduct a methodical and thorough search of the crime scene for evidence.

The method of search depends on: Location Size of the area Complexity of the crime Number of investigators available (You want there to be enough investigators to adequately cover the area, but not so many that they get in each other’s way.)

A large area may be divided into smaller segments with each being searched systematically in turn. This type of approach is called a Zone or Quadrant search.

Other search patterns include:

Lane, line or strip search in which a line of officers move forward side by side in a pattern that covers the entire area.

Grid search

Spiral Search in which officers move in a spiral starting either from the perimeter and moving in toward the center, or start at the center and move outward.

Wheel search - each officer starts at the center and moves outward in a straight line

Legal Considerations for a search:

The 4th amendment guarantees the right to be free from unreasonable search and seizure. To protect this right police are required in most circumstances to obtain search warrant signed by a judge.

To obtain a search warrant police must convince a judge that they have a good, solid reason for the search (Probable Cause).

In the affidavit filed requesting the warrant the police must specify: the location to be searched the items sought the reasons they expect to find those items at that location (the Probable Cause)

The warrant gives police the right to search, but also sets limits on that search. For example if a warrant only specifies the suspects house, then the suspect’s car and a storage shed on the property could not be included in the search.

The search can only include places at that location where it would be reasonable to expect to find the items listed on the warrant. For example if the warrant listed crates of weapons, then a draw would not be a reasonable location to search, since a crate would not fit in the draw.

If a police officer opened a draw and found a weapon, or drugs the officer would not be permitted to confiscate them and they could not be used in court.

To avoid these issues police will often include adjacent buildings, the suspect’s cars, etc in the search warrant request, as well as a number of small items, such handguns, drugs, etc. in the affidavit. They must however be able to demonstrate to the judge that they have probable cause for all items and locations listed.

Conditions in which a warrant is not required:

Emergent Situation: When an emergency exists and someone’s life or health is in danger police may enter a building, structure or vehicle without a warrant. Any evidence collected in the course of dealing with that emergency is usable in court.

If the police leave the scene and then return later to collect additional evidence they will need a warrant for the subsequent search.

Impending loss of evidence: Where a suspect or some outside influence, natural disaster, etc threatens to destroy evidence before a warrant could be obtained police have a right to enter and collect that evidence.

They will have to convince a judge afterwards that they had enough probable cause to enter and that a warrant would have been granted if time had permitted.

A person is legally arrested: At the time of an arrest any property/location the person has immediate control of is open for search. This includes the location/property/vehicle present at the time of the arrest.

Consented search If an officer asks for permission and that permission is granted anything found in that search is admissible in court

For example: The police come to your house and ask your parents if they can search your room for drugs. If your parents say yes then any drugs, drug paraphernalia or weapons found are usable in court.

Airport security searches are considered to be consented searches since you know at the time you bought the ticket that you and your luggage could be searched prior to boarding the plane. Buying the ticket, therefore, implies consent to be searched.

Types of Evidence What to search for and the types of evidence collected at a crime scene depend upon the nature of the crime.

In a homicide the search would center on the weapon and the types of evidence that could have been transferred between the victim and the assailant.

In a burglary the search would include tool marks, or damage at the points of entry to determine if there was a forced entry and on fingerprints.

In a hit and run the outside and undercarriage of the car would be searched for trace evidence of contact between the car and the victim, i.e. traces of paint, broken glass, etc.

Types of evidence may include, but are not limited to: Fingerprints Footprints Tool marks Fibers Hair Blood DNA Body Fluids Tire tracks Victim’s clothing Bullets and shell casings Hand swabs Fingernail scrapings (for gunshot residue)

The size of the evidence can vary from the size of a truck involved in an accident to microscopic particles of skin and hair. Specially equipped vacuums are sometimes used to find small, trace particles.

Some evidence requires special chemicals and/or lights to locate and identify. To find small items searchers will use a flashlight held at an angle, close to the surface being searched. This type of oblique lighting casts an elongated shadow making the object easier to spot.

Packaging evidence The goal is to maintain the evidence in as close to its original condition as possible.

Each piece of evidence should be packaged separately to avoid cross contamination, altering, obscuring or erasing evidence. The only exception to this is where the evidence in attached to something and the relationship between them may be important, in this case the two will package together and an attempt will be made to insure that the relationship remains intact.

General considerations: Wet items must be dried to prevent mold/mildew. Containers should be sealed to prevent loss of evidence and leaks Biological items should be dried and placed in a freezer. 4) Items with trace evidence attached should be packaged with the item attached if possible.

General considerations: Firearms are fixed rigidly in a wooden container Arson evidence is placed in airtight containers so that any volatile chemicals such as accelerants cannot evaporate. 7) Samples of known/control sources will be collected whenever possible.

Chain of Custody A written record of who has possession of the evidence at all times form the time it is collected until it is used in court must be maintained. Any gaps in this record may make the evidence unusable in court.