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DNA recovered at a crime scene often results as damaged; this represents enormous difficulty for the correct typing because of fragmentation or the lack of DNA region of interest. In this work a set of biological samples was prepared and stored under different conditions; STRs and SNPs typing was performed at regular interval of time in order to study the effects of natural DNA degradation. Allelic/locus drop-out phenomenon for the higher molecular weight loci or no results were obtained for microsatellite analysis after 1 week. SNPs typing gave positive results depending on storage conditions and type of substrate; a nucleotide alteration (C to T) was observed for M269 locus in a sample after 3 months. D 2006 Elsevier BV All rights reserved.