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Using the technology available to forensic investigators today, it is not currently possible to distinguish (with certainty) whether a fingerprint is above or below a layer of ink. This has implications where a suspect's fingerprint may be found on a document, but they claim to have handled the paper before any ink was put down on the paper, e.g. "I only put the paper in the drawer". Furthermore, most of the techniques destroy the sample, which in a forens ic context is not recommended. Fundamental experiments analysing fingerprints and inks on basic substrates such as silicon and paper have been carried out. A protocol for determining the deposition order of overlapping undeveloped fingerprints and inks using time-of-flight secondary ion mass spectrometry (ToF-SIMS) has been developed. The developed protocol is based on using the normalised standard deviation of the intensity of an ink line, where that ink line overlaps with a fin gerprint. This method produces a numerical value for the sample, thereby removing any potential human error in judgement when imaging the sample alone. After further testing it was shown that this first protocol was not robust. A new method and protocol was developed based upon using the entirety of the data produced in the secondary ion image. This new protocol is based upon using the fingerprint ridge pattern as a mask on the ink line signal, rather than using line scans, which are less representative of the data collected. Further research revealed that when samples involving a fingerprint overlapping with ink are chemically developed the ability of the protocol to identify the deposition order was affected. In some samples, the chemical development process appears to have had a positive effect on the protocol. The results presented indicate that diazafluoren-9-one immersion could be used preferentially over ninhydrin when investigating questioned documents. These results could affect the order in which forensic investigators use different chemical development techniques to analyse evidence. Currently it is common practice to use more than one technique to develop fingerprints. The results presented Summary could lead to recommendations about the order in which chemical development techniques are used. Techniques, such as ToF-SIMS, require the use of a vacuum chamber into which the sample is placed for analysis. Currently, there is no published literature on the effect that low pressures systems (such as vacuum chambers) have on the chemistry of fingerprints. This research shows that pressures as low as 2xlO·3 Torr have the ability to remove 20-26% (depending on the exact pressure) of a fingerprint's mass. This suggests it would be beneficial to develop high pressure systems in order to carry out analyses in order to detect all chemical species present in a sample. It was also found that some vacuum chambers can in fact add mass to a sample (believed to be from chemical contamination).

Anthropometry can be used in certain circumstances to facilitate comparison of a photograph of a suspect with the potential offender portrayed in video surveillance crime footage. Anthropometry does not have the same success rate in identification as DNA or fingerprinting. However, these types of evidence are not always left at crime scenes. Sometimes the only evidence available relating to an offence is from surveillance videos and research was needed to lend credence to anthropometry as a viable method of identification. An alternative method of detecting individuals from surveillance video, morphology, was also investigated to determine its accuracy in confirming the identity of individuals based on facial descriptions and for use as a comparison tool in forensic identification. Pilot Laboratory Study: A number of different techniques are employed in facial image comparison of living persons. In this study, the effect of rotation on angles and proportions between selected facial landmarks is evaluated as a first step to assess whether facial anthropometry could be usefully applied to facial image comparison. The faces of five volunteers were photographed in the Frankfort plane at different angles of rotation from 0º (frontal) to 90º (side view), rotating every 10º both clockwise and counter-clockwise. Four landmarks were used: right and left ectocanthions, nasion, and stomion. The proportions of the measurements between these landmarks were calculated as well as the angles created by the lines connecting the same landmarks. The results show a consistent and predictable variation between the five subjects. With rotation, the greatest variation is seen where horizontal landmark connecting lines are combined with the ectocanthion/stomion or nasion/stomion lines. There is less variation in the proportions for vertical and diagonally orientated landmark connecting lines. In principle, the data from these empirical measurements could also be used to develop a photogrammetric model of the face which, if calibrated, could be used to correct anthropometric measurements for distortions caused by a camera angle which differs from the one specified in a protocol for facial comparison. The purpose of developing such a model would lie in its use to calculate correction factors to convert observed proportions and angles back to the full-face orientation values, which could then, for example, be used to search a database of the proportions. Investigation of Uncertainty of Anthropometric Measurements: The objective of this study was to estimate the uncertainty in the measurements of the chosen facial proportions caused by landmark placement and by operators taking photographs, including the uncertainty contributions resulting from different people performing these tasks. The aim of this was to simulate effects found in the real world, as there would be different operators both placing landmarks and taking suspect photographs in various police departments. In addition, this study was completed in order to address variables encountered in the Pilot Laboratory Study that occurred as a result of the experimental set up. The first section of the study reviewed the errors involved in measuring facial proportions as a result of variations in landmark placement. Intra and inter-operator studies in landmark placement were conducted and as expected the average and range of coefficients of variation for the set of proportions were larger in the inter-operator error than that obtained in the intra-operator error. The second section of the study reviewed the errors in measuring facial proportions as a result of the process of taking photographs. The lowest variation in facial measurements was seen in the series of photographs taken of a single subject by a single operator and in general, the lowest variation in facial measurements was seen at 45° and the highest variation at 20°. The contributions of errors from landmark placement and photography were determined to produce an overall estimated uncertainty of 5%. When a comparison of 2D images is conducted in this manner this estimation of uncertainty should be taken into account. Anthropometry Study: An existing database of video and photograhic images was examined, which had previously been used in a psychological research project with the aim to test the hypothesis: “Using a comparison of anthropometric facial proportions, it is possible to discriminate between individuals of two samples.” Material avaliable consisted of 80 video (Sample 1) and 119 photograhic (Sample 2) images and were of high resolution, though taken with different cameras. A set of 37 anthropometric landmarks were placed measuring 59 proportions to conduct within sample and between sample comparisons using the following calculations; mean absolute value between proportions, Eulcidean distance and Cosine θ distance between proportions. First, the statistics of the two samples were examined to determine which calculation best ascertained if there were any differences between faces which fall under the same conditions. Subsequent to a between sample, the removal of up to 50% of the lowest variant proportions along with the determination of a subsample of faces requiring human verification were tested. Relative frequency distribution histograms were created from the data and the normal histogram curves of true positive and true negative faces were superimposed to determine their separation rate and how likley it may be to mix up the two categories of faces. Presented results showed that the Cosine θ distance equation using Z-normalized values was the preferred equation because it achieved the largest separation between true positive and true negative faces. Results also indicated that there was no benefit to removing up to 50% of the lowest variant proportions in the comparison of Sample 1 against Sample 2. Finally, applying the Cosine θ distance equation allowed a decrease to five database images to be verified by a human in approximately 75% of the cases tested. Morphology study: A morphological analysis was conducted on high resolution images and although highly relevant to the process of facial identification did not contribute to the continuity of the thesis and thus was included as an Appendix. The morphological analysis was performed on a total of 199 images: 119 photographs and 80 images from video using a checklist of 20 facial characteristics. Each facial characteristic had numerous choices in which it could be described. Once the analysis on all 199 images was carried out, a comparison was conducted between each video (unknown) image and the database of 199 (known) images. In the research conducted, only 2.5% of the comparisons showed a true positive match between video and photograph with zero false positives in the group. Subsequent to analysis it was determined not possible to differentiate between individuals, however, when looking directly at the individuals’ photographs, it is clear that there were differentiating characteristics amongst them. Conclusions: After embarking upon a series of anthropometrical investigations using high resolution images to compare video images with photographic images, it was concluded that anthropometry, when used as a comparison method of identification, does not generate the results necessary for use as evidence in a court of law. Identifying individuals based on a morphological analysis of a check list of features alone also did not result in clear consistent identifications. If descriptions of facial characteristics are to be fully utilized, a side by side comparison is likely to be less subjective. This outcome was as expected and provides additional insights into forensic morphological research.

Σήμερα οι διωκτικές αρχές χρησιμοποιούν αυτόματα βιομετρικά συστήματα αναγνώρισης τα οποία αξιοποιούν βιομετρικά χαρακτηριστικά ατόμων προκειμένου να αναγνωριστούν δράστες εγκλημάτων. Στην παρούσα εργασία έγινε προσπάθεια συσχέτισης αυτής με το αντικείμενο των εγκληματολογικών εργαστηρίων των διωκτικών αρχών. Έτσι δημιουργήθηκε βάση φωνητικών δειγμάτων και κατασκευάστηκε σύστημα αναγνώρισης ομιλητή σε περιβάλλον Matlab με στόχο την μελλοντική αύξηση της βάσης δεδομένων αλλά και την μελλοντική δυνατότητα συνδυασμού: α) εξαγομένων χαρακτηριστικών, β) μεθόδων σύγκρισης των κατανομών φωνητικών δειγμάτων και γ) μεθόδων ταξινόμησης έτσι ώστε να αυξηθεί η απόδοση και να γίνει περισσότερο αξιόπιστο το σύστημα. Το σύστημα που σχεδιάσαμε έχει τα εξής χαρακτηριστικά: α) full automatic, β) open set και γ) text dependent & text in dependent. Από κάθε φωνητικό δείγμα εξάχθηκαν οι mel frequency coefficients με την εργαλειοθήκη Auditory Toolbox, Malcolm Slaney. Η σύγκριση των χαρακτηριστικών των δειγμάτων ομιλίας υλοποιήθηκε με δυο μεθόδους σύγκρισης : Α) Μια διαδικασία που την ονομάσαμε 3Μ (minimum-mean-maximum) η οποία χρησιμοποιεί την Ευκλείδεια απόσταση για την εύρεση αποστάσεων μεταξύ σημείων των κατανομών. Β) Το Wald – Wolfowitz Test (WW-Test ), που στηρίζεται στην θεωρία των γράφων. Τέλος για την ταξινόμηση χρησιμοποιήθηκε ο K-NN ταξινομητής (K – Nearest Neighbor Classifier). Από τα εξαγόμενα αποτελέσματα των μετρήσεων καταλήξαμε στα ακόλουθα συμπεράσματα. Τα όποια σφάλματα προέκυψαν οφείλονται κυρίως στον τρόπο εξαγωγής των mfcc χαρακτηριστικών και λιγότερο στην μέθοδο ταξινόμησης και στον συγκριτή που χρησιμοποιήθηκε. Με την χρήση συνδυαστικά επιπλέον χαρακτηριστικών και ταξινομητών το σύστημα θα γίνει περισσότερο αξιόπιστο. Το σύστημα με μελλοντική αύξηση της βάσης θα μας δώσει ακόμη καλύτερα αποτελέσματα. / Today the law enforcement agencies use automatic biometric identification systems, which utilize human biometric features in order to identify criminals. This thesis was correlated with the objective of forensic laboratories. Hence, a data base of human speech samples and a speaker identification system were developed using the Matlab software. The scope was to increase, in future, the number of the data base samples and to combine features, comparison and classification methods. The system is full automatic, open set, text depended and text independent. From every speech sample, the mel frequency coefficients using the Malcolm Slaney Auditory Toolbox was extracted. The comparison of the speech samples was implemented with two methods: 3M and WW-Test which are based on the graph theory. Finally, the K-NN classifier was used for the classification of the speech samples. From the system evaluation, we conclude that the feature extraction method has the main effect on the system performance. The combination of several features, comparison and classification methods improves the reliability of the system.