The core tenet of physical evidence collection is that an offender leaves traces behind at a crime scene – while taking other traces with them. The concept is Locard’s Exchange Principle, and has been increasingly applied to fingerprints, body fluids, touch DNA, pollen, and near-invisible signs of contact.
Could perfumes and colognes be the next clue?
Key parts of chemical signatures are transferred by direct contact, according to a new study by University College London researchers in the journal Science and Justice .
“While there is a lot of work in forensic science on transfers – for example, the transfer of fibers or the transfer of gun-shot residue – until now there has been no research on the transfer for perfumes,” said lead author Simona Ghergel, a doctoral student, in a UCL statement. “We thought there was a lot of potential with perfume because a lot of people use it. We know about 90 percent of women and 60 percent of men use perfume on a regular basis.”
A series of volatile organic compounds are in a wide variety of common perfumes and colognes. Some of the most common are limonene, linalool, geraniol, eugenol, and coumarin.
The UCL researchers concocted a test mixture that includes those key chemicals, as well as other assorted ingredients included in many scents. Samples of the test perfume were allowed to dry and “age” prior to the experiments – for as short as five minutes, to six hours or even seven days.
Then they conducted a series of experiments to determine whether direct contact, or rubbing, could transfer the signature. The contact was as quick as one minute, and as long as an hour. Rubbing with a gloved hand lasted two minutes. The subject surfaces were then measured for microscopic traces by gas chromatography-mass spectrometry.
The transfer depended on how strong the perfume was, how it aged, and how long the contact was. But transfer happened . Direct contact for just one minute left behind 15 components of the original 44 in the signature, they said.
The drawback is – the evidence disappears after it is collected. It would need to be analyzed almost immediately, they said. “There might be a considerable time delay between the crime and the collection of the evidence, in addition to a delay from collection to the analysis of the evidence, which can make an accurate interpretation of perfume trace evidence difficult,” they write.
Even though the proof-of-concept experiments won’t immediately translate to crime scenes, they contend they could eventually part of an important toolkit, particularly when it comes to sexual assaults.
“Due to the close contact between the victim and assailant during sexual assault, fragrance analysis has the potential to be an additional forensic tool that could be used to demonstrate a contact has taken place, and potentially indicate thy type of contact made and the timeframe since the contact,” they contend.
The potential for first measuring odor in textiles was proposed by a Polish scientist in 2003, in an industry journal. However, the scientist contended such analysis would require massive research to properly quantify.
Hidden apps are growing in popularity. While initially marketed as a way for teens to hide videos, photos, forbidden apps, and text messages from the watchful eyes of parents, the use of hidden apps is quickly expanding. Hidden apps are increasingly used for criminal activity. At the local level, they can be used as a tool to facilitate drug transactions, sexual assaults, child-porn, as well as data exfiltration and theft. On a much larger and more dangerous international scale, these apps can be used for recruitment purposes by ISIS and other terrorist groups.
Because hidden apps are becoming more common sources of evidentiary data in criminal cases, it is essential that forensic investigators take the time to learn about them. Otherwise, key evidence could be missed. When it comes to hidden apps, awareness is critical. Forensic examiners must know these apps exist and how to find them.
While there are many hidden apps on the market today, new ones are introduced virtually every day. A quick Internet search is an excellent way to stay current on what’s available and trending in the world of hidden apps. Along with knowledge of what’s out there, examiners must know how apps and data are being hidden to ensure they are not overlooked.
Types of Hidden Apps There are three main ways to hide apps. Some users manipulate their phones to hide things in places where they don’t belong. Others use apps that are designed to hide other apps inside. Then there are “official” hidden apps (also known as decoy apps), which appear to do one thing while they are actually designed to do something else. One of the most popular hidden apps is the calculator app.
These apps are fully functioning calculators with a twist. Once a password is entered, a new interface appears that allows users to access and store pictures, videos, documents or files that are otherwise hidden to someone reviewing data on the phone.
A less technical, but commonly seen way to hide apps is for the user to create folders or nests of folders on their phone that appear to be harmless, and then to store data they wish to hide within that folder. They may even install an application that allows them to change an app’s icon so that it appears to be a different app on the phone.
Hidden apps reinforce a valuable lesson in the world of forensics, just because you don’t see something initially, doesn’t mean nothing is there. While it is not realistic to expect examiners to stay current on each and every app, knowing they exist and might be installed is essential. During an investigation it is wise to consider a hidden app might be in use, which means a deeper dive is necessary.
Efforts are underway to track down the international syndicates involved in the rhino horn trade, thanks to a new DNA system.
This meant a rhino horn confiscated in Vietnam could be linked back to a crime scene in the Kruger National Park.
“With this it will be possible to identify smuggling routes and more role players than just the poachers,” says Dr Cindy Harper, developer of RhODIS Rhino DNA system. She is also a director at the University of Pretoria’s veterinary genetics laboratory at Onderstepoort.
DNA profiling would help law enforcement agencies find the trafficking route, the couriers, kingpins, and end users. One prosecutor dealing with rhino horn poaching cases welcomed the development.
“The kingpin and the mastermind are the ones we should be prosecuting, and with RhODIS becoming available to international forensic scientists and investigators, we are getting closer,” Ansie Venter said.
"We might soon be able to connect a horn in Vietnam to a poached rhino in the Kruger National Park. What an immense breakthrough.”
Harper said it was introduced in 2010. The database contained information about more than 20 000 individual rhino. Countries using the system included Namibia, Kenya, Zimbabwe, Malawi, Uganda, Zambia, and Botswana.
At a RhODIS Scientific Workshop held in the Kruger National Park recently, it was agreed that the system would form the basis for the international DNA testing of rhino and rhino products. DNA forensic scientists, law enforcement officers and investigators from countries including Malaysia, Thailand, Vietnam, and India attended the workshop.
They were taken to a poaching crime scene in the park, allowing them to see first-hand the savagery inflicted on two rhino killed for their horns. Scientists participated in DNA sample collection training at the crime scene using the forensic sample kits developed for RhODIS. SANParks spokesperson Isaac Phaahla said they supported the collection of DNA as it was part of the criminal investigation.
“We think our colleagues in the NGO sector concentrating on user markets are doing a sterling job,” he said.