Investigations into the influence of donor traits on performance of fingermark development reagents. Part 2: Oil Red O and PD

Latent fingermark samples were collected on white copy paper from 148 donors to compare the relative performance of Oil Red O (ORO; propylene glycol formulation) and physical developer (PD; Tween 20 formulation) on both recently deposited samples and those stored for 30 days. PD, when applied following ORO treatment, was found to outperform ORO on both fresh and stored samples, with ORO performance significantly worsening on older samples. Statistical methods revealed that donor age, sex, and recent use of skin products had significant influence on physical developer performance on recently deposited samples. This variation appeared to decrease with increased sample age. Comparisons of the performances of 1,2-indanedione-zinc chloride (Ind-ZnCl₂) and physical developer showed good complementarity. There was some correlation in that poor Ind-ZnCl₂ performance coincided with poor PD development, suggesting that PD performance is negatively affected by low amounts of eccrine constituents. The lack of other strong correlations between the two reagents reinforce the importance of detection sequences rather than utilizing a single method for fingermark detection.