Every crime scene examiner would undoubtedly been approach by an investigator or detective at some point in their career with the subtle request of trying to get fingerprints off a brick or stone recovered from a crime scene. Usually what follows is somewhat of an awkward silence or raised eye brow from the crime scene technician who is just thinking that this is just another investigator who’s seen the same thing done on CSI, NCIS, or any other Forensic prime-time TV drama.
No doubt there are a few crime scene and fingerprint technicians out there who are currently nodding at this time as they recall when this same experience has happened to them, sometime during their career.
The problem usually is that with stones, bricks, tiles or other similar objects present many obstacles for the technician as to which method to treat the object for any latent fingerprints that may be present. Stones can be porous, e.g. a house brick or shale, or non-porous, e.g. such as a smooth river stone you would skip across the water’s surface when you were a kid. Some stones can be jagged or rough which can make it extremely hard to lift or photograph any friction ridge material you happen to develop.
Yes, stones and bricks are often difficult to treat for fingerprints but there are methods by which you can definitely try to develop suitable friction ridge detail enabling you to perform a comparison.
For stones that you believe are porous, why not try and treat the stone with ninhydrin. Ninhydrin has been used to develop latent prints on porous surfaces since the 1950’s so there’s no reason why it cannot be used here. For non-porous stones, try some magnetic fingerprint powder (black, white, fluorescent) at the crime scene or possibly even cyanoacrylate (super-glue) fuming if you have a chance to bring the stone back to the crime lab.
In a recent case study from the Fingerprint Identification Laboratory of the Israel National Police, this was exactly what they did! They successfully developed sufficient friction ridge detail from both porous and non-porous stone samples, searched the developed prints through AFIS and subsequently, were able to make identifications! In Australia, fingerprints have even been developed off fruit pertaining to a murder investigation!
This just goes to show that regardless of any pre-determined opinions a technician may have on the suitability of a particular object for fingerprint development, you may surprise yourself but what you can do and what you may find if you give it a go.