The Power of a Picture: Identifying people through images of their hands

Expert Profile

Shane Turnidge, a fingerprint expert, has worked in the forensic identification field in Canada for over thirty years. Since leaving the government, he has owned and run SST Forensics, an independent expert fingerprint, and palm print firm. He obtained his expertise, abilities, and experience while working in the Automated Fingerprint Identification System (AFIS) departments of the Peel Regional Police and the Toronto Police Service. He worked as a fingerprint examiner for the government for almost a decade and has identified hundreds of people based on the imprints left by their friction skin.

Throughout his career, he has worked on several high-profile cases and has testified in several court procedures. In recent years, he has also served as an expert witness for the defense. He has been published in many peer-reviewed publications on a variety of issues as an author. He has taught students at the Ontario Police College in Aylmer, Ontario, different palm print analysis and advanced friction ridge analysis courses. He has also instructed at the Kent Police College in the United Kingdom on palm and palm crease analysis. Shane has also given talks on other friction ridge analysis-related subjects at conferences around Ontario and the United States.

Foreground

The images of the hands are common in most cases and so this expert talk delivered by Shane Turnidge has entailed so many interesting pinpoints and important aspects where the image of the hands can be used as the most crucial evidence. And this kind of evidence is often overlooked by the investigation who are unaware of the fact that images can be used to incriminate or exclude subjects. The predominant scenarios of crime where the images of hands can be used as a piece of important evidence to solve the cases are

• Child Exploitation
• Weapons offense
• Drugs related crimes
• Sexual assault and,
• Theft

In this session, the following key points have been discussed by the speaker

• Sources of evidence methodology
• Image clarity
• Clarification
• Pre Calibration
• Things to consider when using images
• Cell phone images, social media
• Case studies

Sources of the Evidence

The sources are the above-mentioned cases where the image of a hand can be taken as crucial evidence in forensic identification and comparison

Methodology

In the identification of the image, there is a certain procedure that is keep being followed to get a better comparison and accurate identification of the person through the image of the hand

 The first step is to flip the hand because when we see the image of the hand it’s always the reverse of the hands in reality. Now for example you have an image of a hand that you have collected from different digital sources such as CCTV or Camera recording and then you have collected the specimen sample for comparison from the suspects. Now if you see the image and the specimen print they both may be in the opposite direction or you can say that they are the reverse so to bring both of them in a similar direction for better comparison the first step is to flip the image. 

The second step is Image Inverting: in the images, the furrows and the major and minor creases usually appear darker and the tops of the ridges usually appear lighter. So inverting the image, essentially creating a negative, makes the surface of the ridge dark and synchronizes the ridges to the known.

So once you have horizontally flipped and then inverted the image then the next step is for comparison This is a fantastic opportunity to clarify the image for better understanding and more in-depth observation of the handprint.

So, to get better and improved clarity in the images while being collected, we can consider clarity, resolution, focus, lighting, and movement of the camera, Camera optics, Size of CCD (Charged Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor) chip, Megapixels, and Orientation of the Hand.

Using photoshop © we can begin the fine adjustments to maximize the image and so to clarify the image further we can adjust the Exposure, shadows, and brightness, and contrast and noise reduction. The greater the contrast between the ridges and furrows, the easier it is to calibrate and encode in an AFIS system. 

Precautions

 In forensic science, there is a high requirement to always follow the procedure and take all the precautionary measures to avoid any kind of errors in the observation and report. We must remember that the process we use to identify peoples skin images is not just subject to the friction ridge analysis but it also involves in the digital a]imaging analysis as well. and hence the standard for the Documentation of Analysis, Comparison, Evaluation, and Verification (ACE-V) (SWGFAST Document) should always be followed

Conclusion

Images of the hand can be the more crucial evidence in cases where there is no other evidence is useful for proper identification of the culprit. The awareness Among Investigators will result in more and more casework And General Acceptance In the court. This type of evidence has no trouble with it in court as forensic protocols are set into it. 

Personal Note

The session is just amazing beyond the imagination. Sir has so amazingly detailed how important the hand images could be if used with some precaution and how significantly they can help to solve the most puzzling cases. A thorough reading is not enough to get the real insight of this session so I would love to suggest all the readers to visit the youtube Channel forensic 365 for a better understanding of the topic and importance of hand images in forensic investigation.