Other important molecules in blood include DNA and RNA present in WBCs; DNA is double-stranded while RNA is single-stranded and can form extensive secondary and tertiary structures . RNA encompasses larger ribosomal RNA and the shorter messenger RNA (mRNA) and micro RNA (miRNA), among others . Ex vivo, DNA and RNA are both degraded similarly; enzymes cleave their phosphodiester bonds most effectively in hydrated environments , which occurs before desiccation of the bloodstain. Reactive oxygen species, alkylating agents and UV irradiation damage the nucleotides and can induce crosslinking, pyrimidine dimers and chain breaks . As a result, base-pairing is disrupted, leading to fragmentation and unstable molecules. However, shorter RNAs like mRNA and miRNA have been shown to persist for long periods in desiccated environments , suggesting that the degradation means suggested above are biased towards larger fragments of nucleic acid. Although RNA might provide insight for long-term studies and complement the short-term degradation of hemoglobin, they have yet to be combined to estimate bloodstain TSD.