Presentation on theme: "Physical Evidence DNA \video projects\ no deals.wmv...\wrongful...\earl washington.wmv...earl washington.wav...\dna\kathleen ham.wmv...\samantha runnion.wmv...\what."— Presentation transcript:
Physical Evidence DNA \video projects\ no deals.wmv...\wrongful...\earl washington.wmv...earl washington.wav...\dna\kathleen ham.wmv...\samantha runnion.wmv...\what is DNA.wmv...\dna contamined.wmv...\larry peterson.wmv \cold case.wmv, \cold hit.wmv \dna\hpd crime lab.wmv
Murder of husband and mother of Federal judge On Feb. 28, 2005 the husband and mother of Federal judge Joan Lefkow were found shot to death in the Lefkow’s Chicago home Suspicion was immediately placed on right-wing militants against whom Lefkow had ruled on a civil lawsuit. A huge investigation got under way. Three days later a West Allis, Wisconsin patrol officer pulled over Bart Ross for suspicious activities. Ross, an unemployed electrician and cancer victim, committed suicide. In Ross’s car was a note in which he confessed to the shootings. He was angry at Judge Lefkow for dismissing his civil lawsuit against medical providers. Ross’s DNA was matched against DNA left on a cigarette butt left behind in the Lefkow residence.
DNA in Girl's Tears Point to Killer, D.A. Says AP, 3/21/2005 According to the prosecutor, DNA from Samantha Runnion’s tears was found in an inside door of the vehicle used by her killer, Alejandro Avila. More DNA material was found on the vehicle’s center console and in scrapings from the victim’s fingernails. Samantha was kidnapped in July 2002 while playing in front of her home with a friend. Her body was found the next day. She had been sexually assaulted and suffocated. In an unrelated case, Avila was acquitted in 2001 of molesting two other girls. On 4/28/2005 Avila was convicted of Samantha’s murder and was sentenced to death.
Court Views Chilling Video of Serial Killer in Action L.A. Times 10/31/05 During a preliminary hearing LAPD showed a videotape of a “husky muscular man forcing a woman onto the ground, raping and strangling her.” Chester D. Turner, 38, is accused of strangling ten women between 1987 and 1998, a period in which he was bouncing around between prison, half-way houses and relatives’ homes. He is suspected in as many as twenty murders, Chester Turner committed during a period in which L.A. averaged 1,000 homicides a year.Chester D. Turner The trail leading to Turner began in February 1998, with the discovery of the body of Paula Vance, 38, who was raped and strangled. In September 2003 LAPD lab analysts extracted DNA from biological samples obtained from Vance’s body. The DNA profile was uploaded to California’s statewide DNA database, which contains prisoner DNA profiles. A match was made to Turner’s DNA profile. A nearby security camera recorded the crime. Although the image is indistinct, the assailant resembles Turner. Additional DNA matches were later made between Turner and biological samples from other victims. These resulted in freeing of David Allen Jones, a mentally- retarded man who served 11 years after being convicted on two of the murders.David Allen Jones
In 1973, Kathleen Ham, 58, a California lawyer, was raped while living in New York city. The trial of her alleged assailant, Fletcher Worrell, ended in a hung jury. Months later Worrell was convicted in another rape and sentenced to prison. After his release Worrell stayed in trouble with the law and eventually left the country. He later returned. In 2004 Worrell tried to buy a shotgun. The background check turned up two sexual assault warrants and Worrell was arrested. Now 59, Worrell has been linked through DNA to 24 other rapes in New Jersey and Maryland. Thirty-two years late, justice is served
First a new trial, then freedom On July 29, 2005, the murder and rape conviction of Larry Leroy Peterson were thrown out after DNA results on hairs and other samples ruled out Peterson as the donor. But prosecutors remained convinced that that Peterson was guilty because he allegedly told several persons that he committed the crimes. In 2006 prosecutors decided not to retry the case. Peterson was originally convicted based on a microscopic hair comparison and testimony of three men who said he confessed to them. But when these men were re-interviewed their stories changed; one suggested he was coached by police. Prosecutors decided to drop the case because they did not feel they had enough evidence to convince a jury beyond a reasonable doubt.
DNA – what is it? Molecules that carry genetic information specific for each person Present in tissue, hair, bodily secretions (e.g., sweat) and fluids (e.g., blood, urine, saliva) Arranged in two strands that spiral G Each strand contains a sequence of “bases”, the chemicals Adenine, Guanine, Cytosine and Thymine Bases are bound across strands, but only in these “base pairs”: G A T G C The only difference between people is in the sequence of these “base pairs” Libraryvideo.com
DNA analysis Complete DNA strands bearing a person’s full DNA sequence are present in the nucleus of every cell Full sequence of base pairs fully identifies a particular person. Can’t be used to make a match (there are too many base pairs in someone’s DNA!) Each person inherits repetitive sequences of base pairs (VNTR, variable number tandem repeats). These occur at certain locations in each person’s DNA strands and can be matched. A lab typically looks at 13 places. The lab counts the number of repeats in each of the 13 places, and the overall pattern is a person's DNA profile. In fact, each place can yield two numbers, because people inherit DNA from both parents, and the number of repeats inherited from each parent usually differs. If the DNA profiles from two samples match, it's considered virtually certain that both samples came from the same person or identical twins. Mom Dad Child
Types of DNA Nuclear: DNA from a cell’s nucleus. It has the complete DNA sequence and has been accepted in Court as positive ID. Mitochondrial: from a cell, outside the nucleus. Present in much greater quantity than nuclear DNA but carries only part of the DNA sequence. – Cannot be used as positive ID but can rule persons out as a source – No general rule allowing its use in Court – Used in Scott Peterson trial: One hair found in his boat was linked to his mother-in-law (both share a DNA sequence that is present in 1 out of 112 Caucasians). – Approved for use in the Samantha Runnion kidnap/murder case YSTR: from the “Y” chromosome, found only in males.chromosome – Cannot be used as positive ID – Useful in sex assaults when female DNA obscures other DNA sequences. – First application in California in the Samantha Runnion case.
Matching known to questioned DNA Compare known DNA, usually an excellent sample taken on purpose to questioned DNA from a scene, often degraded and incomplete Results can be a match, elimination or inconclusive – One dissimilarity (foreign VNTR pattern) eliminates Probabilities can range from 1 in 20 to less than one in a million Errors – Degradation through heat, light, moisture, bacteria – Band shifting – Contamination (coughing, sneezing, skin flaking) – False negatives more common (one dissimilarity excludes) – Technical incompetence and carelessness
Getting DNA “on the sly” -- “surreptitious sampling” Buffalo, NY -- Altemio Sanchez, suspected serial killer, admitted killing three women, gets life in prison. His DNA was recovered by detectives who took a glass that he used in a restaurant Sacramento, CA -- Rolando Gallego, who had passed a polygraph, was suspected in a murder that happened 15 years before. Officers followed him until he discarded a cigarette butt Los Angeles -- Adolph Laudenberg, suspected serial killer, invited by police to discuss an unrelated matter, left his DNA on a styrofoam cup at a doughnut shop
DNA repositories Many States now require felons to submit DNA samples DNA typing is expensive – Time-consuming – Requires precision – Must be careful to avoid contamination Establishing State-wide and National DNA databases has swamped laboratories and created huge backlogs BUT – repositories have led to many “cold hits”, mostly in sexual assaults
Using partial (familial) “hits” to develop investigative leads In April 2008 Cal DOJ announced a program to search for partial hits in the state DNA database As usual, DOJ would compare “questioned” DNA recovered at a scene to “known” DNA profiles in the State database – Normally the State only reports an exact match – In this program, if there is no exact match, the State would ID any persons whose “known” DNA profiles are so close to the submitted, “questioned” DNA that they could be a blood relative For reasons of privacy, agencies would have to make a special request and provide justification before the State would release the identity of persons whose DNA profile was a close hit This procedure is used in Great Britain, but at this time California is the only State in the U.S. to institute the practice
Probability that a match can happen at random (meaning, to an innocent person) Best match -- high a priori (before DNA) probability – A good “questioned” sample from the scene, with repeats present in 10 or more areas, AND – The match was made to a previously ID’d suspect’s “known” DNA – Probability of a random match is often very low -- 1 in 100 million or more Worst match -- low a priori (before DNA) probability – The questioned sample is degraded, with repeats present in only 7 areas (minimum required in California for a match), AND – The match to “known” DNA was produced by a database run – Probability of a random match depends on the prevalence of the DNA profile AND the size of the database – If the same DNA profile is present in 1 out of every 1,000,000 persons, and the database is contains 1,000,000 profiles (like Calif.) the probability of a match after the whole database is run is 1 in 1. If the population is 38,000,000 and nothing else is known the probability of someone matched being guilty is 1/38. – Database matches most useful when questioned (recovered) DNA is so good that the DNA profile is shared by very few people, or when excellent evidence of guilt is independently developed
Virginia Governor Orders Review of 150 DNA Cases by Crime Lab NY Times, 5/7/05 An error in examining the DNA of semen found in a rape victim, which nearly led to the execution of the wrong person, led Virginia’s governor to order a complete review of all cases handled by the lab’s director, Jerry Ban. The lab twice failed to identify the donor of the semen found in a victim even though he was a known, convicted serial rapist. With the DNA unidentified, there was nothing to keep Washington from taking the blame. Auditors from the American Society of Crime Laboratory Directors sharply criticized the Virginia lab, once thought to be the nation’s finest, for caving in to pressures from the State’s former Governor to quickly solve cases. Earl Washington, Jr. Innocent but nearly executed
Houston PD crime lab scandal Major report in June 2007 cited poor procedures and poorly trained personnel The lab’s work was called seriously deficient across the board, casting doubt on thousands of convictions Poor analyses were found of firearms evidence, controlled substances, DNA and serology, the science of typing body fluids. The panel called for a review of 180 cases in which serology was used to determine whether the lab’s findings played major role in securing convictions. So far, serology and DNA errors led to three known wrongful convictions: – Ronald Taylor - failed to find the real perpetrator’s DNA on victim’s bed sheet – Josiah Sutton, exonerated and released from prison in March 2003 when DNA tests challenged the HPD work on a 1998 rape. – George Rodriguez, served more than 17 years in prison in the 1987 rape of a 14-year-old girl before new evidence discredited the HPD findings Full reportSummaryInvestigative panel website