Forensics Ch 2

Rough Sketch

a draft representation of all essential info and measurements at a crime scene; drawn at crime scene -accurate depiction of dimensions of scene -location of all objects important to case -objects located in sketch by distance measurements from two fixed points (i.e, walls of a room) -all measurements made with tape measurer

Chain of Custody*

a list of all people who came into possession of an item of evidence -adherence to stand procedures in recording location of evidence, marking for identification, and properly completing evidence submission forms for lab analysis help with court --avoid questions of authenticity and integrity of evidence

Finished sketch

a precise rendering of crime scene, usually drawn to scale -care taken for aesthetics -Computer-Aided drafting (CAD) is used to reconstruct from rough sketches.

Buccal Swab*

a swab of the inner portion of the cheek; -cheek cells are usually collected to determine the DNA profile of an individual.

The value of crime-scene photographs.

can show layout of scene, positions of evidence, relation of objects at scene to one another. -taken from multiple angles, photos can show possible lines of sight of victims, suspects, or witnesses -accurate description of scene must be available to investigators for future analysis. -also documents biological evidence in original condition, which is often altered during testing

Quadrant or Zone Search Pattern

divides scene into zones or quadrants -team members assigned to each section -sections can be subdivided into smaller sections for smaller teams to search thoroughly -best for scenes covering large areas -must include all probable points of entry/exit used by criminals

Recording the crime scene

have limited time with undisturbed crime scene -includes notes, photography, and sketches. -useful during investigation and also required for presentation at a trial to document the condition of the crime site and delineate location of physical evidence -personnel and monetary limits prevent use of photos at every crime site, so department guidelines establish priorities for photo resources

Packaging evidence

place each different item or similar items collected at diff locations in separate containers, to prevent damage through contact and cross-contamination

The mark of a trained and professional crime-scene investigative team is...

the accomplishment of securing and isolating the crime scene, which are critical steps in an investigation.

The mark of a skilled investigator is...

thorough collection and proper packaging of standard/reference specimens and substrate controls.

Handling evidence

-must handle and process phys evidence in a way to keep change from happening between time evidence is taken, and time it's received by lab. -such as via contamination, evaporation, scratching/bending, careless or improper packaging -latex gloves/ disposable forceps can prevent this

At a crime scene, personnel should never...

do anything: -eat, drink, adjust temperature, open windows, adjust AC, flush toilets, smoke.

Strip or Line Search Pattern

Best for scenes when boundaries well established. 1)One or two investigators start at boundary at one end of scene, walk straight across to other side 2) Move a little farther along border and walk straight back to other side.

Wheel or Ray Search Pattern

Several people move from one boundary straight toward center of scene (inward) or from center straight to boundary (outward). -areas between rays aren't searched, though.

Submitting Evidence to the Lab

Personal delivery or mail shipment -method determined by distance of lab and urgency of case. -postal regulations restrict shipment of certain chemicals, live ammunition, explosives. -most labs require an evidence submission form -each item is to be packaged separately and given a number or letter, listed in orderly and logical sequence on the form.

Once a search for evidence has happened, the team...

...marks the location of all evidence and describe each in their notes. -observe and record state of body of a victim before medical examiner/coroner moves it. -preliminary identification of a victim/suspect should be recorded

To take a bloodstain from a crime scene, one may...

...scrape the stain off the surface, transfer the stain to a moistened swab, or cut out the area of the object bearing the stain.

If evidence has been moved/removed before photography...

...this fact should be noted in report, but evidence shouldn't be put back in order to take photos

Sketches

-done after photos are taken -serves important legal functions -can show layout of indoor or outdoor crime scene and relationship in space of all items and features -illustrate location of collected evidence -allows speculation of paths of entry, exit, movement through scene

Ensuring Crime-Scene Safety

-increasing spread of AIDS and hepatitis B provides hazards. -both normally spread through exchanged body fluids, intravenous drug needles and syringes, and transfusion of infected blood products. -inoculation can easily prevent hep B infection in most people -the federal Occupational Safety and Health Administration (OSHA) requires law enforcement agencies offer hep B vaccinations to al officers who may have contact with body fluids on the job, at no expense to the officer.

"Mincey v Arizona" case

-legality of a four-day search at a homicide scene. -police officer pretended to buy drugs, then forced way into Mincey's apartment, and was killed. -police found tons of evidence, and sent it to trial -but b/c of the illegality of the search, the Supreme Court let him go

Legal considerations at the crime scene

-material is often deemed as legally unusable as evidence b/c of "unreasonable" search and seizure of evidence -any removal of evidence from a person/crime scene must be done with conformity to Fourth amendment.

Photography

-photos must be unaltered -unless injured people are involved, objects must not be moved until they've been photographed. --otherwise, photos might not be admissible as evidence at a trial.

Conducting a systematic search for evidence

-thorough search for physical evidence must be conducted at once, no matter what. -avoid accusations of negligence, charges of "covering up" evidence. -investigator assigns those to search a crime scene -use of forensic scientists at crime scenes usually unnecessary, begins at lab. -some police agencies do have skilled technicians to photograph and search for physical evidence at crime scene

Packaging biological materials

-unbreakable plastic pill bottles for hair, glass, fibers -manila envelopes, sealable plastic bags, metal pillboxes for trace evidence -charred debris from suspicious fire must be sealed in airtight container to prevent evaporation of volatile pretroleum residues --new paint cans, tightly sealed jars

Small amounts of trace evidence can be packaged in...

...a druggist fold. -fold one end of a paper over by one-third, then fold the other end one-third over that, repeating process from other two sides. Afterwards, tuck outside two edges into each other to produce a closed container that keeps specimen from falling out.

Before the scene is sketched, photographed, or searched, the lead investigator...

...carries out an initial walk-through -takes notes on crime scene -write in a bound notebook, ink, at the time of the crime-scene investigation

A minimum chain-of-custody record would show...

...the collector's initials, location of the evidence, and date of collection. -any transfer of individual, or to a lab, must be recorded in notes/etc. -anyone who possesses the evidence must keep a written record of its acquisition and disposition

When collecting biological materials...

...use only disposable tools -don't store airtight, or moisture may accumulate and grow mold, destroying value of blood. -instead use wrapping paper, manila envelopes, paper bags. -must handle with minimum personal contact to avoid infections or contaminating the evidence; face masks, shoe covers

Guidelines to protect investigators at crime scenes with potentially infectious material (pg 45-46) 1-4

From the International Association for Identification Safety Committee 1) At scenes like a homicide, personnel wear doubled latex gloves and protective (Tyvek-type) shoecovers; liquid repellent coveralls in large contamination areas. 2) particle mask/respirator, goggles, or face shield in presence of possibly infectious dust/mist; 3) Processing/collecting evidence, be alert to sharp objects; place in appropriate containers. 4) potentially infectious materials at crime scene, retain a red biohazard plastic bag for disposal of contaminated gloves, clothing, masks, pencils, etc. Afterwards, must be taped shut and sent to approved waste pickup site.

Video recording: Pros and Cons

Pros: -becoming increasingly cheaper, and thus more popular -combine notes and photography Cons: -shakes, zoom can be sloppy. -blurry stills. -extra noise can obscure narration. -if videotape is used instead of digital, it can deteriorate cuz tape is sensitive -still surpassed by photography

Search Patterns

Strip or Line, Grid, Spiral, Wheel or Ray, Quadrant or Zone search pattern. -depends on location and size of area, actions of suspects and victims at scene -one person should supervise and coordinate collection of evidence when possible --avoids confusion, duplicated effort.

Grid Search Pattern

Two people perform line searches originating from adjacent corners, form perpendicular lines -very thorough -boundaries must be well established to use this method well, though

Substrate Control*

Uncontaminated surface material close to an area where physical evidence has been deposited; -this sample is to be used to ensure that the surface which a sample has been deposited doesn't interfere with lab tests -ex: normally collected at arson scenes. If an investigator suspects a surface has been exposed to gas etc, should also collect a piece of same surface material that is believed to NOT have been exposed to gas. --at the lab, substrate control's tested to ensure that surface which accelerant was deposited on doesn't interfere with testing procedures.

Spiral Search Pattern

Usually one person; investigator moves in an inward spiral from boundary to center of scene, or outward spiral from center to boundary. -perfect spirals are difficult, evidence can be missed -inward spiral, move from area light in evidence to heavier -either approach, easier to locate footprints

Physical evidence*

any object that can establish that a crime has or has not been committed, or can link a crime and its victim or perpetrator

Critical areas of the crime scene should be...

vacuumed, with the sweepings sent to the lab for analysis -portable vacuum cleaner with special filter attachment

Standard/Reference Sample*

physical evidence whose origin is known, such as blood or hair from a suspect, that can be compared to crime-scene evidence. -few investigators seem aware of the importance of supplying this to the crime lab.

Michigan v. Tyler

-business establishment leased by Loren Tyler was destroyed by fire; extinguished in early hours of the morning -too hard to see, to conduct an investigation; building left unattended until 8 AM when inspection began. Items collected that day, 4 days, 7 days, and 25 days after fire, all made without warrant or consent. -Tyler and partner were convicted but supreme court held reversal of conviction. Only initial morning search was proper, but subsequent evidence was inadmissible.

DNA Evidence

-can be detected by saliva, sweat, or skin cells. -sources include stamps, licked envelopes, gum, bedsheet. -key concern is contamination --preventable by face mask, disposable latex gloves, possibly coveralls -must take all clothes from victim and suspect, and send it to the lab.

Mobile Crime laboratory

-carry necessary supplies to protect crime scene; photograph, collect, and package physical evidence, and perform latent print development. -better name would be "crime-scene search vehicle"

Notes

1) Call a crime-scene investigator to the scene 2) identify person who contacted investigator, time of contact, any preliminary info disclosed (case number) 3) When the lead investigator arrives, the note taker should record date and time of arrival, who's present, and identities of other personnel who are contacted. -if additional personnel are contacted, names, titles, and time of arrival should be recorded. -investigators must keep a precise record of personnel movements in and out of the scene, beginning with an interview of the first responding officer in order to record his/her movements.. -also important to record tasks assigned to each member of a team, as well as the beginning and ending times for processing of scene.

Allowances for a warrantless search

1) emergency circumstances 2) need to prevent immediate loss or destruction of evidence 3) a search of person or property within immediate control of the person provided it is made incident to a lawful arrest 4) search made by consent of parties involved

Two approaches to crime-scene photography

1) film -sheet of light-reactive grains 2) digital -microchip turns light into pixels -mostly used -can be easily manipulated, though -many jurisdictions set guidelines for determining when digital photos can be used, establish and e,force strict protocols for image security and chain of custody.

Photographic Procedures

1) overview photos of entire scene and surrounding area, points of exit and entry, taken from many angles -all walls if took place inside. -adjacent rooms to crime scene also photographed like this. 2) If there's a body, must show position and location relative to entire scene -close ups showing injuries, weapons near body. -surface beneath body 3) items of phys evidence as discovered, showing position and location relative to scene. -use scale when necessary. 4) can string digital images together to create near 3-D panoramic view of a crime scene.

Video Recording: how to

1) should include entire scene and immediate surrounding area -long shots as well as close-ups taken in a slow, systematic manner. -have one crime-scene investigator narrate the evens and scenes being recorded while another videos.

Aside from pen and paper, these methods can also be used for note-taking.

1) tape recorder -can be taped fast, hands free, and security feature of preventing erasure/taping over if security tab on tape's removed 2) narrating a videotape -combines notetaking and photography -must be transcribed eventually, though

Securing and Isolating the Crime Scene

1) the first officer arriving is responsible for preserving and protecting the area as much as possible; note any vehicles or people leaving scene -evaluate victim's condition and record any statements -first priority is getting medical help for people who need it and arresting the perpetrator 2) More officers arrive, boundaries made to isolate area. Ropes, barricades, guards -detain potential suspects or witnesses still at the scene, exclude unauthorized personnel. -responding officers must keep an accurate log of who enters and exits the scene 3) Onse secured, lead investigator evaluates area. Determines boundaries of scene and establishes perpetrators path of entry and exit. Identify, document, and photograph obvious items of crime-scene evidence 4) Investigator proceeds with an initial walk-through of the scene to gain an overview of the situation and develop a strategy for systematically examing and documenting the entire crime scene.

Things to be collected and sent to a forensic lab

1) victim's clothing 2) fingernail scrapings 3) head and pubic hairs 4) blood (for DNA typing) 5) vaginal, anal, and oral swabs (in sex-related crimes) 6) recovered bullets from the body 7) hand swabs from shooting victims (for gunshot residue analysis)

Guidelines to protect investigators at crime scenes with potentially infectious material (pg 45-46) 5-8

5) note taking done wearing uncontaminated gloves. Pens/markers disposed of before leaving scene. 6) immediately remove soiled/torn individual protective equipment. -then personnel must disinfect/decontaminate potentially contaminated body areas using a recommended solution, cover area with clean replacement protective equipment. Once departing, this should be repeated on body areas where contamination could have occurred 7) eating, drinking, smoking, applying makeup are prohibited at immediate crime scene 8) nondisposable items (lab coats, towels, personal clothing) that may be contaminated should be placed in a yellow plastic bag labeled "infectious linen" and laundered at expense of employer, by a qualified laundry service.

Locating physical evidence

investigators must rely on experience from past investigations to successfully recover relevant physical evidence -homicide case, look for weapon or evidence as a result of contact between victim/assailant (hairs, fibers, blood) -look for tool marks at point of entry in a burglary