DNA Evidence Identification, Collection & Preservation For Law Enforcement Presidential Initiative March 11, 2003 • “Initiative to Advance Justice Through DNA Technology” • 6 different DNA issues to include training for law enforcement officers • The result is critical pieces of evidence will be collected, fewer cases will be jeopardized by mishandling and more cases could be solved. Purpose •Utilize available technologies •Improve conviction rates •Exonerate the innocent DNA Evidence and Bio-safety Universal Precautions • Treat every item as though it were contaminated with blood or other body fluids • Use Personal Protective Equipment • Face mask/shields • Safety glasses • Gloves • Disposable cover-alls • Shoe covers Contamination Practices • Educating crime scene personnel • “touch evidence” • “clean” practices” • If possible, use disposable instruments to pick up items • Otherwise, clean items with 10% bleach & alcohol between samples • Try not to touch the area you want tested! Contamination Practices • Use of cell phones in the crime scene may result in inadvertent contamination of an item if gloves have not been changed • Change gloves with EVERY item! • No smoking IN the crime scene The Crime Scene Proper Collection, Packaging & Preservation of DNA Evidence Securing the Scene Identify focal point of scene and extend outward to establish scene boundaries Securing the Scene • Limit number of people with access to scene • Keep log of all personnel that had access to the scene – for elimination samples Image of Stop sign with crime scene contamination tips Documentation • Essential to establish: – Location – Condition – Chain of custody for each item collected Types of Documentation • Notes • Diagrams • Photographs • Video and audio Potential Sources of DNA Evidence • Clothing • Hat/Cap sweatbands • Eyeglasses • Earrings • Chewing gum •Toothpicks • Toothbrushes •Food • Bottles or cans • Water bottles • Gloves • Watches • Condoms • Bite/Lick/Suck marks • Used tissues • Licked stamps • Handkerchiefs • Envelopes • Cigarette butts Common DNA Sources Blood • Victim or Suspect’s body • Weapons • Clothing • Other items at scene or transported away from scene Common DNA Sources Semen • Victim/Suspect’s body • Clothing • Towels • Bedding • Condoms/devices Common DNA Sources Vaginal Fluid • Suspect’s pubic area • Suspect’s underpants • Suspect’s fingers • Condoms • “Devices” Common DNA Sources Saliva • Victim or Suspect’s body • Underpants • Expectorant • Bitemarks • See “Oral” evidence Common DNA Sources Oral • Items coming in contact with someone’s mouth • Items left behind by V or S • Careful!! Consider the probative nature of time, location, and mobility!! Common DNA Sources Hairs • Individual’s pubic area • Clothing • Crime scene Recognition of Hairs/Fibers • Consider the probative nature of hairs/fibers • Domestic situations • Boyfriend-girlfriend • Use oblique lighting DNA Sources Urine and Feces • Victim and Suspect underpants (sodomy) • B&E scenes • Vandalism scenes 24 DNA Sources Touch • Casual contact between a person’s hand(s) and an item • GLOVES?? • Intentional use, unintentional DNA loss • MIXTURES!! Caution Regarding “Touch” DNA • Carefully weigh the value of a possible latent print against a possible DNA profile • “Touch” DNA is not meant to replace latent prints! DNA Sources Wearer Items that are: • In contact with a person’s body • Items left behind by V to “mark” location • Items discarded by S (inadvertently or not) • Careful!! Consider the probative nature of time, location, and mobility!! Knowledge into Practice • Look at the following crime scene photos and identify the following: • Salivary DNA sources • Probative “touch” DNA sources • Probative “wearer” DNA sources Knowledge into Practice Image of bathroom Knowledge into Practice Image of car in woods Knowledge into Practice Image of bank Knowledge into Practice Image of clothes strewn on bushes Knowledge into Practice • Look at the following pictures and identify potential sources of DNA Knowledge into Practice Image of childs bedroom On-Scene Blood Detection • Visually • Look for red/brown/green/black stains •Luminol/Bluestar • Quick and easy screening tool when blood may be present BUT IS NOT VISIBLE! Before Image of carpet After Image of carpet with lumniol Before Image of fabirc After Image of fabric with luminol BLUESTAR Image of wood without bluestar Image of wood with bluestar BLUESTAR Image of road without bluestar Image of road with bluestar 41 Luminol/Bluestar • Advantages • Screening tool • Sensitive • Easy to use • Talk to YOUR laboratory! Caution!! • Chemical screening tools are not specific for blood • Metals, bleach, cleaning products, treated lumber, animal fat, and itself • Always examine positive reactions and surrounding areas in regular light for visible staining • If blood-like stains are seen,DO NOT use! On-Scene Detection of Semen • Visually •White or cream-colored stains 44 On-Scene Detection of Semen • Alternate light sources (ALS) • UV, Omnichrome, Luma-Lite, Crimescope,CrimeLite ALS Principle • Different substances react differently to light Detectable Body Fluids •Urine •Semen •Saliva •Vaginal Secretions •Sweat ALS Rules • Semen stains reflect specific light differently than the background fabric • May be darker than the background • May be lighter than the background Light Sources • Location/screening use • Not confirmatory • Detection ability based on fluid & fabric • All ALS stains NOT semen stains • All semen stains NOT detected with ALS False Positives • Laundry detergents: • Contain phosphors (appear brighter in sunlight) »Sunlight contains UV light making whites whiter »Dark pigments absorb the UV light and don’t glow What to Collect • Anything to link suspect, victim, weapon, crime scene • Anything to clarify what happened • Known Standards • Blood or oral swab • Hair • Control area “Known” Standards • Known victim, suspect, and elimination samples: • Eliminates the need for repeated analyses • Enables a more discriminating search of the data bank • Ensures that it’s the suspect’s profile being searched • Enables more discriminating statistics and conclusions Control Swabs • An unstained area near the stain collected • Check with your laboratory regarding their preference for collecting control swabs 53 Small or Mobile Items Collect and submit entire item •Knife •Shoe •Hat Large or Immobile Items Submit portion of items • Cutting: carpet, car seat • Swabbing: linoleum • Lifting: glass, counter top • Scraping: cement wall • Absorbing: wet blood Probative Value • DNA is a very stable molecule and can remain intact for many years • Not every item at a crime scene should be considered probative evidence Probative Value • The best evidence occurs •When a victim’s or suspect’s DNA is found where it is not supposed to be Packaging of Evidence • Dry items should be packaged in porous containers such as paper bags, envelopes, boxes Packaging of Evidence • Wet items should be allowed to air dry prior to packaging • Very wet items can be transported in plastic containers but should be air-dried as soon as possible Chain of Custody • Key to the proper resolution of a criminal investigation • All the work in the lab is meaningless if the chronological history of the evidence is not maintained Transportation of Evidence • Extended exposure to heat or humidity causes degradation to biological evidence • Packaged items from the crime scene need to be moved to a suitable storage facility as soon as possible 61 Transportation of Evidence • Liquid samples should be transported in refrigerated or insulated containers • Evidence should be stored in a temperature controlled facility Evidence Storage • The hallmarks of proper evidence storage include: • Paper packaging • Items are “sealed” • Items from a single case are kept together when possible • Items are kept away from heat sources • Chain of Custody is current Collection of Evidence Proper Collection, Packaging & Preservation of DNA Evidence Rule of “Thumb” • It’s better to collect it and not submit it than to not have collected it at all! • Keep lines of communication open between you and the laboratory Amount to Collect • Early DNA - Size of quarter • Serology - Size of dime • Current DNA - If you can see it, we can try it Collection of Blood • Evaluate the item/stain and its probative value • Swab the stain (works best on non-absorbent surfaces) • Scrape the stain • Cut the stain from the item • Collect the item Swabbing the Stain • Lightly moisten the swab (distilled or sterile water) • Rub swab over the stain, rotating swab • Use 2 - 4 more swabs Swabbing the Stain • Concentrated!! • Better to collect it and not use it rather than to lose the sample altogether • Don’t sacrifice other exams!! (latents!) Collecting the Item • Recommended • When staining pattern is important • Item is difficult to swab • Item requires multiple exams • Make sure the item is dry • Package to ensure integrity (glass, sharps, breakables) Collection of Semen • Evaluate the stain and its probative value • Swab the stain • Works best on non-absorbent surfaces • Cut the stain from the item • Collect the item Possible Victim Vaginal Fluid • From suspect pubic area or fingers • Lightly moisten the swab (distilled or sterile) • Swab the entire area, rotating the swab • Use no more than 2 swabs Victim Sexual Assault Kit • Standardized kit to collect pertinent biological evidence from the body of the victim • Contact your local laboratory to determine which kit they use Suspect Standard Kit • Standardized kit to collect pertinent biological evidence from the body of the suspect • Contact your local laboratory to determine which kit they use Collection of Hairs/Fibers • Post-It notes placed into envelope or Ziploc bag • Straight into Ziploc bag NOT recommended due to static electricity • Gloves or forceps to transfer hair/fiber(s) into a glassine envelope • Vacuum is generally not recommended • Talk to YOUR laboratory! Collection of Saliva • From a bitemark: • Moisten one swab and swab area of mark • Follow with a dry swab to collect any remaining moisture on skin • Allow swabs to air dry and package together • From Suspect Pubic Area • Refer to vaginal fluid instructions Known Saliva (Buccal) Swabs • Known standard • Swab the inside of the cheek area using 2 swabs • Rotating them during collection • Allow swabs to air dry (or place in swab box) and package together Fingernail Scrapings/Clippings • Collect only when indicated • Clip nails into clean paper with a cleanclipper • Separating left and right nails OR • Scrape the underside of each nail onto a clean paper • Package the scrapers inside this paper Bone • Co-mingled remains, mass graves, skeletal remains, exhumations, airplane crashes • Marrow is where blood is made • Good to use if no blood is available • Best to collect rib bone or vertebrae • Place in jar and freeze Teeth • DNA is in the dental pulp • Very resistant to decay • Obtained from teeth of mummies • Saved baby teeth can be used as secondary DNA standard in missing person cases • Collect into pill box Organs/Tissue • Collect if no blood is available • Collect liver or spleen • Place in jar and freeze Data Bank Samples • Follow your state or local protocol for collecting samples from arrestees and/or convicted offenders Knowledge into Practice • Look at the following items and determine the best way to handle the object Knowledge into Practice Image of hammer and chisle Knowledge into Practice Image of hair on clothing Knowledge into Practice Image of cigarette butt by doorway Knowledge into Practice Image of wrist watch Knowledge into Practice Image of object with stain Knowledge into Practice Image of ski cap in garden Knowledge into Practice Image of chweing gum Knowledge into Practice • For the following items, indicate how you would collect the evidence Knowledge into Practice Image of stone walkway Knowledge into Practice Image of stain on car window Knowledge into Practice Image of broken window with blood Packaging Materials • Paper bags • Plastic bags* • Pill boxes • Envelopes and note pad • Paint cans • Cardboard boxes • Evidence tape • Specializedmaterials • Glass jars Packaging Techniques Choice of proper container • Paper is the packaging material of choice • Plastic should only be used when there is danger of liquids (biohazard or other) penetrating Packaging Techniques Air-Dried • Evidence should be allowed to air-dry • The optimal method to preserve DNA Packaging Techniques Tissue and liquid samples •Keep refrigerated Caution!! Never freeze liquid tubes of blood Be careful, put glass tubes in plastic bag Packaging Techniques • Package items separately when recovered separately • If items found together, then package together • Clothing in a pile • Cigarettes in an ashtray Packaging Techniques • Don’t allow fluids or stains to touch each other or unaffected areas Packaging Techniques Minimize interior movement Packaging DNA Evidence Unacceptable • Plastic • Multiple items per bag • Stains still wet • “Mummy wrap” Acceptable • Paper • One item per bag • Stains air-dried • Do not overfill bag Labeling Packages • Name/initials of the collector • Each person/entity subsequently having custody • Date of collection or transfer • Agency and case # • Victim or suspect name • Brief description of item Labeling Packages • Label container before packaging Labeling Packages • Label and identify exterior as to content Labeling Packages • Label the item with warnings/hazards or other helpful information: • Biohazard • Sharp • Fragile • Unloaded • Etc. Sealing the Package • Seal packages with tape • Prevents items from falling in • Prevents items from falling out • Provides measure of security – evidence can’t be accessed unless seal is broken • Initial across seal or under the seal Sealing the Package Acceptable • Scotch tape • Packaging tape Unacceptable • Masking tape • Staples Identify the Packaging Error Image of cigarette butt in plastic Identify the Packaging Error Image of knife sticking through paper bag Identify the Packaging Error Image of 2 cotton swabs in same plastic bag Image of 2 dna swabs in same plastic bag Preserving DNA Evidence Acceptable • Keep cool •Bring to lab as soon as possible Unacceptable • Keep warm •Delay in transport to lab Trunk Storage Summary DO • Air dry before packaging • Use paper • Use separate bags • Use plenty of room • Seal with scotch tape • Initial with permanent marker • Keep item cool Summary DON’T – Package item still wet – Use plastic – Clump in one bag – Use smallest bag –Staple shut – Initial with ballpoint pen – Keep in trunk in July Now What? • Are you familiar with your lab’s DNAtesting policies? • Do they… •Work all types of cases? •Work cases regardless of the submissionof a suspect sample? •Work both subject and non-subject cases? • Contact lab personnel for assistance inevaluating evidence with respect to the lab’s policies and capabilities Time to Submit! • Follow your agency’s and forensic lab’s policies •Meet in person? •Submit only pre-approved items? •Special times & locations for submission? •Specific directions? •Prioritization? –i.e., if you get results on A, don’t worry about B…. • Continue the investigation while waiting for results! Laboratory Analysis Proper Collection, Packaging and Preservation of DNA Evidence Where is DNA Found? Epithelial cell Sperm cell Tissue cells White blood cells Typically Encountered Samples Image of cotton swab, blood spatter, blood vials, clothing, semen Evidence Screening Image of technician Blood Examination *Never assume a red stain is blood* • Presumptive testing • Confirmatory testing • Human origin testing *Cannot tell age of a bloodstain* DNA Blood Facts O Located in white blood cells O If you can see it, we can test it O Transfusions do not interfere with typing Semen - General Rules • Primary indicator of sexual activity • Begin with body swabs, then to clothing and bedding • With successful analysis of semen, limited further analysis will be performed Semen Examination • Presumptive testing • Confirmatory testing •P30 •Sperm Human Sperm Image of sperm How Many Sperm? • Average Human Male •Deposits 3-6 ml of semen •1 ml semen = > 100 million sperm •Possibly over 600 million sperm!!!!! • Vasectomized Male •Deposits 0 sperm How Long Can Sperm Last? • Normally ~3-4 days in vaginal cavityof living woman • Normally ~12 hours in rectal cavity of living person • Normally ~6 hours in oral cavity of living person How Long Can Sperm Last? From the Forensic Literature: • Found in frozen body’s vaginal cavity after 19 days • Found in frozen body’s rectal cavity after 3 years • Found in mummified body’s vaginal cavity after 3 years Reasons For Not Finding Sperm • Acidic environment • Multiple ejaculations • Low sperm count • Time • Poor quality sperm Reasons For Not Finding Sperm • Victim bathed • Suspect didn’t ejaculate • Bacteria ate them • It didn’t happen DNA Semen Facts • Found in sperm head • Need 100 sperm heads for testing • Can separate sperm DNA from other cells in stain (vaginal cells) Saliva Examination • Presumptive •Amylase • No confirmatory test Hair Examination • Hair or Fiber • Human or animal • Body area • DNA located in root • Microscopic comparisons rarely performed Urine • Concentration varies, depending on time of void, dilution by fluid ingested •Chemical detection tests are available • Probative nature of urine • Epithelial cells may be used for DNA, depending on the amount Fecal Material • No serological testing for identification • Kits available for DNA testing from fecal material What is DNA? “The Blueprint of Life” DNA Structure and Location • Four bases: A, T, C, G • Spiral staircase (Double helix) • Genes and non-coding regions • All nucleated cells Location of DNA in the Cell Image of mtDNA Useful DNA Facts • Inherited • Same only in identical twins • Stays the same for life • Same in every cell • Stable in dry conditions DNA Analysis • PCR amplification •Copies small amount of DNA •Look at 16 different areas of DNA •STR Typing •“1 in 100 million billion” •Identity statement DNA Analysis •Step 1 • Extract and purify DNA •Step 2 •Quantitate DNA Analysis •Step 3 • Amplify (make copies) •Step 4 •Separate and detect PCR Amplification of DNA Image of PCR amplification process PCR Advantages • Requires small sample size • Old/degraded samples may give results • Can be automated Future of DNA Testing • Mitochondrial DNA (mtDNA) • Transmitted through maternal line • Works on samples without nucleus (hair shafts) Future of DNA Testing • Y Chromosome DNA • Transmitted through paternal line • Useful in resolving DNA mixtures in sexual assaults Future of DNA Testing • Automation • Relieve backlog • Process offender samples • Miniaturization • Portable, typing done at scene • Direct access to database from scene Future of DNA Testing CODIS (Combined DNA Index System) • Convicted offender profiles • No suspect cases • Cold cases Future of DNA Testing NDIS (National DNA Index System) • Re-examination of old cases where conviction was based on non-DNA evidence Cold Case Testing What is a “Cold Case”? “…cases that other investigators, for whatever reason, could not solve.” --Bureau of Justice Assistance Bulletin Reasons for Cold Cases • Rising crime rates • Staff shortages • Budget restrictions Reasons for Cold Cases •“Do more with less” • Changing forensic laboratory policies • Changing forensic laboratory priority/backlogs Law Enforcement Responsibilities • Identify cases with remaining biological evidence • Of these cases, determine if material witnesses or victims are available • Identify statute of limitation issues -APRI Law Enforcement Responsibilities • Define categories of cases • Case review Cold Cases • Locate case files •Reports •Evidence logs •Forensic testing reports •Previously tested evidence •Crime scene evidence containing biological evidence Law Enforcement Responsibilities Remember Cold hits begin the investigation rather than end the investigation! Cold Cases • Evaluate probative DNA evidence & submit appropriate evidence for testing • Consult with prosecutor & laboratory • Continue investigative protocol Cold Cases • Identify witness issues • Follow agency procedures for submitting DNA profile to CODIS • Prepare a John Doe warrant if applicable If a “Cold Hit” is Obtained • Identify other unsolved cases believed to have been committed by the same offender • Confirm the availability of biological evidence in those cases -APRI If a “Cold Hit” is Obtained • Locate the suspect identified by the hit • Obtain a confirmation sample • Interview that suspect • Complete the investigation Unadjudicated Cold Hits In the event the crime cannot be adjudicated, it may helpful for: • Leverage for plea agreements • Evidence of other crimes/bad acts -APRI Unadjudicated Cold Hits In the event the crime cannot be adjudicated, it may helpful for: • Enhancement of punishment at sentencing hearings • Information to withhold parole Evaluating Cold Cases for DNA • Previous case activity – No viable suspect(s) – No evidence to link developed suspect(s) • Review the case file – Investigative reports – Photographs – Evidence recovered – Forensic reports Evaluating Cold Cases for DNA Is the original investigator of assistance? Locating Cold Evidence for DNA • Locate and document the evidencepackages •Police storage? •Court storage? •Laboratory storage? •Attics, desks, and vehicles? •Destroyed? • Chain of Custody? Evidence Evaluation • Evaluate evidence with respect to the forensic laboratory’s capabilities • Use a Forensic Scientist to assist this process! Evidence Consumption • US Supreme Court found that “[i]n general, the destruction or failure topreserve potentially useful evidence doesnot constitute a violation of the due process clause, unless it can be shown thatthe police, the prosecutor or the laboratoryacted in bad faith.” • Arizona v. Youngblood, 488 US 51 (1988) • Dixon v. State, 275 Ga. 232 (Georgia Supreme Court 2002) -APRI Evidence Consumption • “Half” Rule observed by some laboratories • No more than half of the evidence sample may be consumed • Repeat testing? Not possible by the original laboratory • Check with your forensic laboratory to determine policy Cold Evidence • Each item of evidence has a history – can’t go back in time! • Unintentional historical contamination • Police and crime scene personnel • Scientists – both DNA and other examiners • Jurors, lawyers, and some judges! Overlooked Cold Evidence • TOUCH evidence • Handles of weapons, ligatures, etc. • WEARER evidence • Items of clothing, masks, etc. • ORAL evidence • Bottles, utensils, etc. Important DNA Principles To Consider • DNA continues to degrade over time, although more slowly in cool, dry environment. • mtDNA may also have been used in these types of cases Advantages of Applying DNA to Cold Cases • Advanced DNA capabilities •“Do more with less” evidence sample • Results are more discriminating » Not to be confused with “accurate” • Use of DNA Data Bank in the absence or elimination of a suspect •State • National (NDIS) Post-Conviction Testing Law Enforcement Responsibilities • Identify which cases • Were closed before DNA evidence was available to the jurisdiction • Still have biological evidence remaining and the location of that evidence • Resulted in a conviction of a person who is still alive -APRI Post-Conviction Cases • Share many of the same evidence issues as cold cases • Must consider possible contamination by – Attorneys – Judges – Juries from original trial How DNA Helps Solve the Crime Image of flow chart Cold Case Summary • Computerization of DNA profiles will enable us to: • Solve no suspect cases • Connect cases that no one knows were perpetrated by the same individual Cold Case Summary • It’s never too late torevisit cold cases • We are able to use all parts of a human to solve crimes, from head to toe! CODIS Combined DNA Index System • Enables state & local crime labs to exchange and compare DNAprofiles electronically CODIS Contains two database files: • Convicted offender file »Contains DNA profiles of offender convicted of a qualifying offense • Forensic file »Contains DNA profiles developedfrom crime scene evidence CODIS • Convicted offender file match • Obtain warrant to confirm match • Forensic file match • Investigators from differentjurisdictions can exchange information CODIS •Possible outcomes: •Link 2 or more unsolved cases •Link a solved case to an unsolved case •Link 2 or more solved cases Using Results Understanding “Hits” and “Misses” The “Reality” of DNA evidence in our society. Reality vs. T.V. • Public perception is influenced by TV. • Crime solved and offender brought to justice within an hour • DNA collection at crime scenes is increasing • Technology improving • DNA processing takes time! Public Perceptions • Latent fingerprint technology improving • People expect police to locate & collect prints at crime scenes • With increased knowledge of DNA • People expect DNA collection at crime scenes Fingerprint vs. DNA • “Swabbing” for DNA and“dusting” for fingerprints • Overlap conceptually but not practically • DNA labs able to perform more tests with less evidence • Fingerprint brush can transfer DNA between crimes Who’s the Bad Guy? • Police are taught not to leavefingerprints at a crime scene • It’s nearly impossible NOT to leave your DNA • Some agencies require fingerprints & DNA profiles of officers entered into databases. DNA “Hit” and “Miss” “HIT” = a person’s DNA was left at the scene – Friends and family leave DNA behind – “hit” might not be that important. “MISS” = A failure to find evidence. – Doesn’t mean someone is not responsible for a crime. – The person’s DNA might not be in the database. DNA History • DNA collection was not possible prior to 1950’s. • The discovery of DNA structure by Watson and Crick • Police able to link people to crimes • Failure to link a person to a crime by DNA does not mean “not guilty” Strategic Uses for DNA Evidence • Prove guilt • Exonerate the Innocent • Paternity Testing Strategic Uses for DNA Evidence • Determine identity of human remains • Evolution of human populations –National Geographic • Study inherited disorders DNA in the Courtroom • Circumstantial Evidence • Information collected from witnesses • Documents pointing an individual as the perpetrator DNA in the Courtroom • Physical Evidence • Information collected from actual objects •Bodies •Stains •Weapons •Fingerprints •Body Fluids •Hairs, Fibers, etc. DNA in the Courtroom • Prosecutor must present evidence to the court • Must prove an overall “theory” from evidence to jury • Scientific evidence is precise DNA in the Courtroom • Evidence can be: • Documents • Exhibits • Facts agreed on by both sides • Testimony of witnesses Scientific Evidence Admissibility Standards • Is the scientific evidence trustworthy? • Must demonstrate »accuracy (validity) »consistency (reliability) Scientific Evidence Admissibility Standards • Frye Rule •U.S. v. Frye (1923) •Standard on accepting scientific evidence. • People v. Kelly (1976) •Proponent of the evidence must demonstrate the correct use of scientific procedures