Background: Recovering deoxyribonucleic acid (DNA) from degraded skeletal remains is a key challenge in forensic science. Factors such as thermal exposure, microbial activity, and ageing reduce DNA quality, hindering DNA profiling. This study aims to optimise protocols for DNA extraction from partially burnt, exhumed, and aged bones using the EZ1 automated system. Methods: Bone and tooth samples were cleaned thoroughly and dried before processing for extraction. A tooth or a cut portion of cleaned bone was finely powdered by grinding and decalcified using 0.5 M ethylenediaminetetraacetic acid (EDTA). Proteinase K digestion was performed, and carrier Ribonucleic Acid (RNA) was added to enhance DNA yield. DNA extraction was carried out using the EZ1 Advanced XL system. Quantification was performed using the Quantifiler Trio Kit. STR profiling was conducted with the Investigator® 24plex QS Kit and analysed via capillary electrophoresis. Results: The modified protocol enhanced both DNA integrity and consistency. Exhumed bones exhibited the highest DNA yield (0.258 ng/μl), followed by partially burnt bones (0.072 ng/μl) and aged bones (0.013 ng/μl). All samples yielded amplifiable STR profiles. The inclusion of carrier RNA and the use of automated extraction effectively minimised DNA degradation and contamination. Conclusion: The protocol proved effective in retrieving amplifiable DNA from degraded bone samples. Its success across various bone types highlights its applicability in forensic identification. The use of automation enhances both efficiency and reliability, making this method suitable for mass disaster scenarios and the analysis of historical remains.

Keywords: DNA extraction; STR typing; human identification; tooth; bone;  capillary electrophoresis.