Case solved using CODIS

Case solved using CODIS

Combined DNA Index System (CODIS) is a computer system that includes local, state, and national DNA profile databases obtained from convicted criminals, evidence DNA profiles from a crime scene, and missing person DNA profiles. The goal is to connect various crimes and identify possible perpetrators by comparing DNA samples from crime scenes with samples of convicted offenders (Panneerchelvam, & Norazmi,2003). Whenever new samples are entered, they are compared to those stored within computer systems.

In the case of Jane Britton (then a student at Cambridge) murdered on Jan. 6, 1969. Jane had gone for a date at Charley’s Pub with the boyfriend that evening, and shortly after returning home and the boyfriend had left for the night, she went for a glass of sherry before finally returning to her apartment. She was found lying on her bed. Autopsy showed fractures in her skull, contusions in her head and brain lacerations, all leading to her death. DNA was collected and due to lack of proper technology, the killer would not be identified. It was till 2018 that a breakthrough was finally found by the Middlesex County District Attorney’s Office. The profile they made of DNA corresponded to a sample already contained in CODIS, which belonged to a man named Michael Sumpter, who was by then working on Arrow Street a mile from Jane Britton’s apartment. Sumpter had been arrested three years after the death of Jane for physically assaulting a woman at Harvard Square MBTA. In 1975 he was already out of jail but then sent back to prison for 15-20 years for raping a woman in her Boston apartment. Sumpter died in 2001. Sumpter’s DNA sample was linked to 23-year-old Ellen Rutchick’s rape and murder in her Beacon Street Apartment in 1972. He was also linked to the rape and murder of Mary Lee McClain, 24, in her Mount Vernon Street Apartment in 1973. In 2018, 17 years after he died, investigators finally compared Jane’s killer profile closely enough with Sumpter’s brother to conclude that Michael Sumpter was the man who, on the evening of Jan. 6, 1969, apparently raped and murdered Jane in her apartment.

Case solved using mDNA

Two men killed Elizabeth Ballard and wrapped her using a plastic. They vacuumed and cleaned the room she was murdered in, so to try and cover up the case. They scoured the trunk of the car in which they were transporting her body to the desert of New Mexico and dumped in a shallow grave. Having tried to block everything that would link them to the murder, a single hair belonging to a dog that was owned by one of them messed them. The hair was found in one of Ballard’s socks. The hair was then sent to a lab in California that was known for its advancements in forensic animal DNA. They were able to link the hair to a bit bull mix known as Hercules. Hercules was already identified to the authorities, since Ballard and her murderers were allegedly entangled in some crazy love triangle, and the killers had already been questioned about her death. Both denied that Ballard was ever in their place, but when the hair turned up on that sock, a hole emerged in their story, and ultimately led to a conviction of murder for both men. The ability to conduct animal DNA testing at a level sophisticated enough for criminal trial use is a product of two developments: the last decade’s astounding advances in human gene-mapping techniques and the creation of genetic databases for various domesticated animal species. The high sensitivity of the mDNA examination allows forensic experts to extract knowledge from old evidence related to unsolved cases and small pieces of evidence containing minimal biological content. In addition, mDNA’s maternal inheritance enables scientists to equate the mDNA profile of a group of residues with that of individual reference samples such as sisters, brothers, mothers, or any other individual related to a missing person. Such samples should have the same mDNA profiles since all maternal relatives share the same mDNA. Since mDNA is maternally inherited and several individuals that have the same form of mDNA, mDNA analyzes can not be used to classify specific identifiers. However, mDNA is an excellent technique to use to collect knowledge in situations where an evaluation of nuclear DNA is not feasible.

Case solved using Y-STR testing.

Y-STR testing is also used in samples that contain a combination of male and female DNA. This normally occurs in cases of sexual harassment, where the two DNA samples are not separable (Kayser, 2017).

When Frances Bloomfield’s body was discovered on Sept. 22, 1997, in a ditch outside Rockford, Ill., police gathered hundreds of pieces of evidence. From boxes of duct tape, maps of Minnesota from inside her vehicle, along with ligatures and plastic used to seal and tie her body, were among the items collected by police trying to locate her killer, but none of these produced a suspect. However, detectives have found evidence linking Bloomfield’s husband, John R. Bloomfield, 73, of St. Paul, Minn., to the murder using a reasonably new method which analyzes only the Y chromosome portion of a DNA profile. In the case of Bloomfield, a Y chromosome sample taken from one of the ligatures used to connect the victim’s body returned “consistent” with the Y chromosome of John Bloomfield according to a criminal complaint. According to investigators, the report presented further proof that led to his arrests – such as a potential motive, lack of alibi, conflicting statements, and a hair on tape from the body of Francis Bloomfield was found to be microscopically identical to the hair of her husband. According to the police, investigators chose to run the old evidence via a new Y-STR check based on discovering male DNA on the binding. DNA experts state that the “Y-STR” DNA study has been around for around five years and is most effective when male and female DNA is mixed.

Nevertheless, even with the latest technologies available, it might take time to recognize instances in which it would be useful, finding resources required to run the experiments and then do the analysis. It should be noted that every male who comes from the same family have the same Y-STR profile hence reducing the statistical power of this analysis. It is also rare to match two people when a different DNA sample is found within the crime scene.

Biological sources of DNA that could be found in forensic casework

According to Park, Beaty, Boyce, Scott & McIntosh, (2005), biological sources of DNA include; Blood, Semen, Saliva, Urine, Hair, Bone, and feces

DNA Extractions

Bloodstain on a shirt- this is done through cell lysis undertaken by adding a detergent/chaotropic-containing solution. The cell membrane is broken or killed to release intercellular materials such as DNA

Postage stamp- uses a steam bath and tweezers that is a source of the false-positive mixtures that are observed in mtDNA sequence data. Since the envelope is filled with water, the DNA of the envelope sender on the outside of the envelope may be mixed with the authentic DNA inside the capillary action seal, and if the tweezers are not used in the same orientation, the DNA may be moved from the outside of the envelope to the inside seal.

Hair shaft (no root)- e PrepFiler BTATM extraction method is used. DNA extractions are quantified using a PCR method in real-time, and mtDNA fragments of varying lengths are then amplified to establish DNA degradation

Vaginal swab containing semen- Typical evidence of sexual harassment involves the victim getting a vaginal swab. According to Lee & Shewale, (2006), naturally, such a sample contains the victim’s epithelial cells and few offender’s sperms (semen) accumulated during a sexual attack. It is therefore required to separate DNA from sperm and epithelial cells to obtain individual genotype. This is done through differential lysis of epithelial cells and sperm in the absence of dithiothreitol generating epithelial cell lysate and sperm lysate. The DNA from these lysates is then purified using traditional DNA purification methods.