Development of solvent-mediated tape separation technology for fingerprint restoration and STR-based genetic analysis

Adhesive tapes recovered from crime scenes frequently function as dual-purpose forensic substrates, simultaneously bearing latent fingermarks and touch DNA, yet their removal from porous surfaces often results in ridge distortion and loss of biological material. This study evaluated a solvent-assisted tape separation protocol using a dichloromethane/ethyl lactate mixed solvent to enable effective tape removal while preserving both fingermark and DNA evidence. A 2:8 (v/v) dichloromethane/ethyl lactate formulation (DCM/EL_28) was identified as the optimal solvent condition, exhibiting minimal substrate damage and superior adhesive control. When applied to three common commercial tapes adhered to corrugated cardboard, DCM/EL_28 consistently produced well-defined latent fingermarks with higher minutiae counts and AFIS-derived similarity scores than two commercially available release agents, Un-Stick and PIC 10, which showed variable ridge distortion or severe adhesive disruption. Following fingerprint development, DNA was successfully recovered from all tape samples, with the majority yielding complete or near-complete STR profiles containing a high proportion of the alleles expected from the corresponding donor reference profiles. This proof-of-concept study demonstrates the feasibility of using the DCM/EL_28 mixed-solvent protocol for tape separation while preserving fingermark and DNA evidence under the controlled experimental conditions evaluated. These findings provide a basis for further validation using a broader range of substrates, tape types, aging conditions, and casework-relevant samples before its potential application in routine forensic practice can be established.