Dynamics of latent fingerprints: The effect of physical factors on quality of ninhydrin developed prints – A preliminar

1. Dynamics of latent fingerprints: The effect of physical factors on quality of ninhydrin developed prints – A preliminary study Om Prakash Jasuja , M.A. Toofany , Gagandeep Singh , G.S. Sodhi พ.ต.ท.ธนบูรณ์ ธัชศฤงคารสกุล รหัส 51312341 ดร.ศิริรัตน์ ชูสกุลเกรียง อ.ที่ปรึกษา

2. The objective The effect of some of exudation of sweat, the type of surface on which latents are deposited, the ability of the donor to deposit fingerprints, contact time, force of contact and their effect on the ability of ninhydrin (1% ninhydrin solution) to develop the marks. Latent fingerprints from good and bad donors were obtained on paper with variable pressure under controlled conditions.

3. The previous work • Thomas [1] studied various physical parameters of fingerprints such as • their formation, droplet properties, contact angles, optical properties and • electrical properties. • Jones et al. [5] discussed a large number of factors including donor • variations, which may affect the development of latent fingerprints and • can play a vital role while formulating and evaluating a fingerprint • development reagent.

4. Overview • Introduction • Fingerprint • ninhydrins • Experiment • Results and discussion • Conclusion

5. Introduction

6. Fingerprints

7. Ninhydrin Chemiscal Properties Formular compound

8. Experimental methods 2.1. Control of pressure 2.2. Control of exudation of sweat 2.3. prepared ninhydrin 2.4. The quality of developed fingerprints

9. study as follows 1.consisted of twenty individuals. 2.consisted of five individuals considered to be good sweat donors. 3. consisted of five individuals considered to be bad sweat donors.

10. 2.1. Control of pressure touchedfinger of the donor on the paper with placed on a flat pan of a balance. deposited at pressure equivalent to 50 g, 100 g 150 g and 200 g.

11. 2.2. Control of exudation of sweat covering the donors hand loosely with a polythene bag for various time periods ranging from 30–180 s. taken off the hands and the index finger was pressed on the paper as mentioned above. stored latent fingerprint sample in paper envelopes.

12. 2.3 Ninhydrin was used as the developing reagent and was prepared as follows dissolved 1.0 g of Ninhydrin in acetone and added 2 drops of acetic acid make volume to 100 mL with acetone stored in the refrigerator and come to room temperature half an hour before use.

13. kept ninhydrin solution between 30 and 35 °C and humidity at 55–65%. latent fingerprintsimmersed ninhydrin solution. dried dry in the open air for a few minutes before being placed in an oven maintained at 100 °C for approximately 2 min.

14. 2.4. The quality of developed fingerprints was graded as follows Fig. 1. Fingerprint depicting poor quality (Grade 2). Fig. 2. Fingerprint depicting medium quality (Grade 3).

15. Fig. 3. Fingerprint depicting good quality (Grade 4). Fig. 4. Fingerprint depicting excellent quality (Grade 5).

16. Results and discussion

17. Table 1 Effect of Physical Factors on the quality of latent fingerprints development

18. Fig. 5. Pressure vs quality at different induced sweating time (IST) n=20 (mixed population).

19. Fig. 6. Pressure vs quality at different induced sweating time (IST) in rich donors n=5.

20. Fig. 7. Pressure vs quality at different induced sweating time (IST) in poor donors n=5.

21. conclusion a linear effect of force applied to deposit fingerprints and the sweating characteristics of a donorcould be established with respect to the quality of the developed prints, but in case of good donors smudging of fingerprints took place when the pressure applied and induced sweating time exceeded 200 g and 180 s respectively. 120 s of induced sweating time produced the same quality of development of the donated fingerprints irrespective of the donor.

22. Thank you