Identification of a crime perpetrator on the basis of DNA fingerprinting is not as easy as some of the CSI shows on television make it out to be. A sample such as blood stain, touch sample or body fluid retrieved at a crime scene is often a challenge for DNA analysts. In many instances, the samples are limited in quantity, found in dirty conditions, exposed to harsh environmental factors and are mixtures of more than one DNA—human and/or non-human. One of the most important aspects of the workflow to successfully obtain a DNA fingerprint profile is accurate quantification of human amplifiable DNA. The more information gleaned from the sample, the better equipped the DNA analyst is to determine the best course of action for obtaining a usable short tandem repeat (STR) profile from challenging samples. Therefore, Promega has developed the PowerQuant™ System, a probe-based 4-target, 5-dye real-time PCR method to a) determine human and male DNA concentrations in a sample, b) detect possible PCR inhibitors c) identify possible mixtures and d) measure DNA integrity. Continue reading “PowerQuant System: Tool for informed casework sample processing decisions”
STR analysis
How a Magazine Ad Helped Convict a Rapist
In May of 1986, a woman in Orange County, Florida, was surprised by a man who entered her apartment and raped her at knifepoint. Despite the fact that she got a glimpse of his face, the chances of identifying and convicting her rapist were slim. Although law enforcement officers did their best to identify the perpetrator, their investigative techniques in the case were limited compared to our current set of forensic tools. That changed when Jeffrey Ashton, an assistant attorney for the state of Florida, saw an advertisement for DNA-based paternity testing in a magazine and began to wonder if DNA testing could also be used to identify the man responsible for the attack.
Continue reading “How a Magazine Ad Helped Convict a Rapist”Update: Is It the Blood of Louis XVI?
In an earlier blog entry, I wrote about the ill-fated Louis XVI, the French king who was famously beheaded along with his wife, Marie-Antoinette, during the French Revolution in 1793. Witnesses to the execution dipped handkerchiefs in the king’s blood and kept them as souvenirs of the common people’s rebellion. In 2010, scientists published the presumptive DNA profile of the king, obtained from one of these bloody handkerchiefs (1). Shortly after this profile was published, doubters surfaced, arguing that scientists could not say with certainty that the blood was that of Louis XVI. Clearly, more work was needed to identify the source of the blood. Recently, additional work was published (2,3). The most recent data (3) were presented at the 2013 International Symposium on Human Identification; these newest data cast doubt on the identification of the remains of not one king, but two.
Continue reading “Update: Is It the Blood of Louis XVI?”Toilet Paper: The Newest Tool in the Fight Against Crime
In July of 2009, the bodies of 43-year-old Alan Grna and his 85-year-old mother Julianna were discovered in their Ohio home—both victims of a violent assault. The lead detective in the case called in the Ohio Bureau of Criminal Identification and Investigation (BCI) to collect evidence from the crime scene, evidence that would lead them to the man who was eventually convicted of their murders. One of the key pieces of evidence was a roll of toilet paper.
Continue reading “Toilet Paper: The Newest Tool in the Fight Against Crime”
The Daughters of King Tutankhamun
The pharaoh Tutankhamun ruled ancient Egypt during the 18th dynasty of the New Kingdom (circa 1550–1295 BC), one of the most powerful royal houses in ancient Egypt. Although he sat on the throne for only 9 years and died at the young age of 19, he is one of the most well known pharaohs, due largely in part to the discovery of his intact tomb by archaeologist Howard Carter in 1922. The tomb was filled with riches befitting a king, including an elaborate sarcophagus with a gold burial mask and statues of ancient Egyptian gods such as Osiris and Anubis, as well as gold jewelry, statues and images of servants, ornate furniture, models of boats and other items that the pharaoh would need in the afterlife. A lesser known item discovered in his tomb was an undecorated wooden box in which two small gilded coffins lay side by side. These coffins held the mummified remains of King Tutankhamun’s two stillborn daughters. Recently, researchers examined these remains in detail to determine their gestational ages and characterize any congenital abnormalities that they might have inherited from the boy king.
Continue reading “The Daughters of King Tutankhamun”Not My Shade of DNA
DNA testing is providing some answers in a nine-month campaign of hate and revenge involving two British women: a wife and her husband’s mistress. Between May of 2010 and February of 2011, the wife was stabbed in the stomach with a screwdriver, had bleach thrown in her face, received death threats in the mail, been the victim of an arson attack and had a threatening message written on her apartment window in lipstick. She blamed the mistress in her reports to police. As a result, the mistress had been arrested numerous times and spent 20 hours in police custody despite her assertions that she was not involved in any of the attacks. The situation became so maddening that her family started a diary of her whereabouts to help prove her innocence.
Hoping to find some physical evidence that might shed some light on the events, police examined the evidence in the case more closely. This included DNA analysis of the lipstick used to write the threatening message and saliva used to seal the envelope containing the death threats. The results of the DNA analysis were shocking. Continue reading “Not My Shade of DNA”
Justice 27 Years Too Late: The William Dillon Story
William (Bill) Dillon spent more than half of his life in a prison for a crime he did not commit. Now, after being exonerated by DNA testing, he is telling his story of injustice and, eventually, freedom. On Wednesday, January 12, he visited Promega Corporation in Madison, Wisconsin, to relate his story and his efforts as an advocate for exonerees who are released from prison with little support from the same justice system that failed them in the first place.
The events that lead to Dillon’s false imprisonment started on August 17, 1981, when a man was found beaten to death in the parking area of a beach in a Florida tourist town. On August 22, detectives were investigating the crime scene, when Dillon and his brother drove into the parking area. Little did Dillon know that his decision to drive to the beach that day would lead to a wrongful conviction and 27 years and 8 months in prison.
Continue reading “Justice 27 Years Too Late: The William Dillon Story”Cells, Specificity and the Seven-Year-Old Brain
We would all agree that being specific is important. But sometimes what it is important to be specific about is not so easy to agree upon.
My seven-year-old son is a good example.
Continue reading “Cells, Specificity and the Seven-Year-Old Brain”