| Author | Message | ||
     Webservant (Member) Moderator Username: Member Post Number: 299 Registered: 03-1997 |
Are RUVIS and/or Super Glue Fuming Wands Worthwhile? Short Answer: No and No, for most local police agencies in most instances. Boring Details: No agencies have the resources to do everything in every case, not even everything in every who-done-it homicide case. Agencies have to balance available resources between what works well most of the time and available manpower (funding). Although I believe1 that every agency performing crime scene examination should have RUVIS technology (or at least indirect access to it through a neighboring agency or supporting forensic laboratory), I do not recommend RUVIS for everyday burglary/B&E/larceny types of crime scenes because of the difficult nature of using the technology, and the even greater difficulty in recording high-quality images. RUVIS should be used at those crime scenes where an agency is doing everything possible2 (such as cyanoacrylate fuming entire rooms) to recover all identifiable impressions. After cyano-fuming, RUVIS can make faint or invisible cyano-developed latent prints appear to glow white on a jet black substrate (though it is not luminescence) because of the reflectivity of short-wave UV light in the cyanoacrylate bloom (the microscopic fibers occurring with high humidity cyanoacrylate development) of the latent print. Shoe prints and latent finger/palm prints in transparent/translucent floor wax are often completely invisible and not otherwise recoverable without RUVIS (the floor wax tends to look like shiny, wet black tar3 with RUVIS). Most smooth, nonporous multicolored substrates appear as jet black surfaces under RUVIS, sometimes providing superior contrast to white light, longwave UV or laser/alternate light source illumination. And, of course, some latent prints are visible with RUVIS without any processing at all. For lesser offense crime scenes that do not warrant days of crime scene examination scrutiny, I recommend examining nonporous surfaces with a strong, white flashlight and magnifying glass before dusting for prints. For those portable specimens that are going to be brought back to the laboratory for complete exam, I recommend on-scene cyanoacrylate fuming with a coffee cup warmer and portable chamber (cardboard box), or packaging in a manner precluding prints from rubbing off during transit to be cyano-fumed elsewhere (this means wedging cans, bottles, knives, guns, etc., corner-to-corner in small boxes or attaching with wire ties to peg board, and not putting such specimens in evidence bags that will wipe the prints off). Generally, small items to be completely processed should be considered as destroyed (not usable after complete processing with dye stains, etc.). For those items/surfaces for which it would not be logical or appropriate to destroy them (such as the interior of a car involved in a simple larceny), dusting with brush and powder (after white light exam and photography) is what should normally be done. On surfaces that are going to be dusted, if an officer sees a good quality impression using his/her strong white flashlight and magnifying glass, it should be photographed as is before dusting or any other processing. This is often best accomplished by shining the light in a manner bouncing the light directly back toward the camera [also called direct reflection], though dark-field illumination (on clear glass surfaces) and other illumination techniques can also be very effective. This photography-first (before dusting) step is important because eccrine gland-deposited latent prints on nonporous surfaces can be very fragile and may be destroyed (break off or be wiped away) during normal dusting. If an officer sees a latent print during white light exam (or even just indications of a latent print), but finds little or no trace of the latent print when dusting with powder, then he/she should consider using breath4 to temporarily deposit enough moisture on the latent print residue so that powder will stick to it (because dried eccrine gland secretions are not normally sticky). In a nutshell, the officer should breathe on the surface heavily to try to fog it, and soon after the circle of condensation evaporates/disappears, dust the print. Some folks call this the "hut" method. Before cyanoacrylate fuming, it was the primary/best method for developing eccrine gland secretion latent prints on nonporous surfaces (such as the many thousands of marijuana baggies processed in crime laboratories). I introduced RUVIS to the English-speaking world at the International Fingerprint Symposium in 1993 at the FBI Academy, having previously been exposed to that technology in Japan when Hamamatsu developed the first devices for the Japanese National Police Agency's Identification Division (I lived in Japan during 1977-80 and 1989-92). Over the many years since the technology has been for sale in America, many agencies have bought the devices, only to take them to crime scenes a few times and then store them away to seldom, if ever, be used again. For many agencies, there were unrealistic expectations of using RUVIS as a fast and easy/simple device at ordinary crime scenes. Agencies have to balance available resources between what works well most of the time and available manpower (funding). Regarding cyanoacrylate fuming wands, I do not recommend them.1 There may be some technology breakthrough in the future that renders them of value over alternative processes, but I have not seen it yet. Fuming wands were a popular item when they first came out over a decade ago, and then most agencies stopped using them after they realized they can harvest more, and better quality, latent prints without using the wands (and without accidental heat damage to valuable property). Do not forget about "powder rubbing" as a last step for processing any nonporous surface you have fumed with cyanoacrylate. If you have unsolved cases where no latent prints were developed on important nonporous specimens, consider pulling out those specimens and applying powder rubbing. It can be successful even many years later. Although you did not ask about using a portable laser or alternate light source to supplement crime scene examination, I believe I should mention that, like computers, alternate light source technology is constantly becoming less expensive, smaller and stronger/better. For about $35, you can easily purchase5 a one watt relatively monochromatic (centered near 455 nm) blue light LED to put in any existing mini-Maglite that uses two AA batteries. By using royal blue (centered at 455 nm) LED flashlights with orange goggles and/or a sheet of orange transparent plastic, you have a poor man’s alternate light source system that rivals the capabilities of systems that cost more than 100 times as much only a few years ago. Google crime scene flashlight to see relatively monochromatic LED-powered crime scene lights starting at about $15. For Lab use, Google blue led grow lights to find 25 to 90 watt royal blue LED light sources that will run from 110 or 220 VAC (be sure to select/use only Royal Blue LEDs). 1 The above comments do not purport to represent the position or opinion of the US Department of Defense, US Army, US Army Criminal Investigation Command, or any other organization with which the webservant was or is affiliated. 2 See Latent Print processing procedures at the CBD IAI website here, and the FBI Laboratory's Processing Guide for Developing Latent Prints here. 3 See reference to invisible shoeprints in wax viewed with RUVIS on page 568, Journal of Forensic Identification, Vol 48(5), 1998. 4 The breath technique to temporarily deposit condensation and thereby cause development of latent prints has been used by law enforcement for decades. References include "Developing Latent Prints on Plastic Bags," Identification News, Vol. 24, No. 9, September 1974, pages 13-14, by John C. Wilson; and “Developing Latent Fingerprints On Aluminum Foil," FBI Law Enforcement Bulletin, Vol. 46, No. 6, June 1977. 5 Blue light (455 nm) LED lights for Maglites are available from this website and other sources. The LED website here is one of several online resources for staying current on LED research. Orange goggles are available for as low as US$16 and orangle plastic viewing (filter) plates are avaialable for as low as US$8 at vendors listed here. | ||
| Webservant (Member) Moderator Username: Member Post Number: 298 Registered: 03-1997 |
The following query is modified from a personal email sent to the Webservant from a US Police Department lieutenant on 16 May 2008: Are RUVIS and/or Super Glue Fuming Wands Worthwhile? I have been trying to evaluate techniques that will help us maximize the amount of fingerprints that we recover from crime scenes. We already fume most movable evidence at the crime scene and then transport it to the lab for further processing. However, considering that natural eccrine gland secretions are often not developed by simple dusting with brush and powder, I am trying to identify ways that we can increase the number of prints that we collect on immovable evidence such as the points of entry and exit at a burglary. To that end, I am seeking advice on your opinion of RUVIS imagers and if you believe that employing a RUVIS at a crime scene might help us increase the number of prints we collect from immovable objects above 50%. Lastly, I am curious if you have an opinion on fuming wands. |
