Technical note: The Next Step - a semi-automatic coding and comparison system for forensic footwear impressions.

Footwear impression evidence is a key tool in criminal investigations, connecting suspects to the crime scene; in addition, it may provide valuable forensic intelligence linking different crime scenes in the absence of a suspect. This paper presents the development of a computer database and semi-automatic system for shoeprint comparison. The database is based on structured manual coding of elements by CSI (Crime Scene Investigators). The computer algorithm then compares the pattern information of the query footwear impression to the entire database, returning a list of possible matches ranked by pattern similarity and crime scene geographic proximity. Initial results using a database of 284 footwear impressions from real crime scenes revealed that a "match" (i.e., the same shoe model) was found for 30% of the impressions; in most cases, the "match" ranked within the top five places of the "hit" list generated by the algorithm. Our results confirm that this semi-automatic footwear comparison system is simple, cost-effective and efficient, providing great potential for linking crime scenes.

Digitally processing an image of a shoe impression in blood.

Shoeprints are valuable crime scene exhibits because, given a reasonable-quality impression and a suspect shoe, the forensic investigator can correlate the impression with the shoe and pin down a suspect. In similarity to bloody fingerprints, a common practice with bloody shoeprints is that the crime scene investigator photographs the impressions at a 90° angle with a scale, develops them with amido Black, and then photographs again. In most cases, the post-development prints will feature better and more details that are usually sufficient to perform a comparison between the impression found at the crime scene and suspect's shoes. This study examined shoeprints in blood that had been collected in an apartment in northern Israel where two bodies were found. The floor tiles in the apartment had featured a colored design which in the post-development photographs of the shoeprints blended in with the blood on the floor. As a result, the shoeprint impression was partial and small details were masked. In the laboratory, we processed the pre-amido Black photograph in several steps designed to increase contrast. The result of this digital processing was a full shoeprint sufficiently clear to display randomly acquired characteristics of the sole and subsequently establish identification between the impression found at the crime scene and suspect's shoes. When chemical amplification is not sufficient, it is worth exploring other methods before proceeding with the comparison, as it is sometimes still possible to extract information from the same data using alternative methods in order to achieve a conclusive result.

Investigation of Different Ways in Which the CODIS 7.0 May be Used in Mass Disaster Identification.

DNA analysis is a key method for the identification of human remains in mass disasters. Reference samples from relatives may be used to identify missing persons by kinship analysis. Different methods of applying the CODIS in disaster victim identification (DVI) were investigated. Two searches were evaluated: (i) relating family relatives to a pedigree tree (FPT) and (ii) relating unidentified human remains to a pedigree tree (UPT). A joint pedigree likelihood ratio (JPLR) and rank were calculated for each search. Both searches were similar in average JPLR and rank. In exceptional cases, namely the existence of a mutation different from the CODIS model, a nonbiological father, a mistake in STR, or incorrect profile association, the UPT search returned one true rank, whereas the FPT search returned no results. This paper suggests a novel strategy to overcome these limitations and increase efficiency in conducting identification of mass disaster victims.