An identification case is presented, in which a body of a deceased man was not recognized by his brother due to the corpse decomposition. The comparative material included DNA originating from the brother of the missing individual. In the Hemogenetics Laboratory of the Forensic Medicine Department, Jagiellonian University Medical College, bone tissue samples were genotyped for 16 STR loci on the chromosome Y and found concordant with the brother's reference sample, except a single locus DYS389I. Extended analysis for 15 autosomal STR loci confirmed that these men were brothers. Thus, a new mutation was encountered in DYSS389I. When included in the biostatistical calculations, the mutation did not diminish the cumulative likelihood ratio of sibship because of the very high likelihood based on autosomal loci analysis and nonexistence of the Y chromosome haplotypes in the known population databases.