Establishing the post-mortem interval (PMI) is often the primary objective in forensic investigations.Whilst various techniques for PMI estimation in terrestrial environments are well researched, reports of techniques for PMI estimation in aquatic environments are scarce. The aim of this project is to establish and validate a method to estimate the time of bone submersion in sea water.Chemical substitutions for foreign ions at the anionic and cationic sites of hydroxyapatite (HA) can occur as can adsorption resulting in structural changes that can be scrutinized using INS and then further analysed through comparison with other spectroscopic findings. Pig bones will be used as human model and maintained in sea water for one week and six months. Grinded bones will be studied without any further preparation and after been deproteinated and defatted. 4 days of beam time will be required.