CLPEX Chat Board

I received an item from a local agency last week that had been treated with Ninhydrin by the agency. Most likely they used a spray can instead of a custom mixutre from a recipe. Had I received it "raw," I would have started out by using DFO first as is our common sequence.

Are there any problems with going backwards at this point and treating it with Ninhydrin? I'm wondering if there are particularly any chemical issues with doing this. I'd like to use our own mixture of Nin on the item, but if it won't hurt to go back and do DFO first, that's the direction I'll take. Then I would continue with our normal sequential procedure.

Any thoughts?

DFO will not fluoresce if applied after Ninhydrin and will therefore not produce any results. You could attempt to reapply Ninhydrin though.

WSP sent me a copy of a study done in California on just this subject. The study indicated that the use of DFO as a post-Ninhydrin procedure can result in the enhancement of ninhydrin developed latent prints, but eliminates the possiblity of a Laser or alternate light source examination. In their conclusions they state that when utilizing the alternative DFO application procedure, noticeable improvements in ninhydrin developed latent prints were observed. On numerous occasions, prints not visible during the initial examination (after ninhyrin processing) were observed after DFO processing. I can fax you a copy if you like.