| Author | Message | ||
     wangyuewz |
officer T. W. Blankenship : Instead of seeing the ridge detail, you're actualy looking at the furrows, due to the way the blood is forced down into the furrows from pressure on the finger tips, when making contact with a surface. on the other hand ,if the fingerprints touched against blood much little ,the fingerprints is the ridge detail. in lab ,some students press bloody fingerprints is such .here is a footprint developed by LEUR6G ,IT IS same as weak bloody fingerprints . sorry ,here can not send a picture ,if you tell me your e-mail ,i can post your picture and development method . wangyue china e-mail :wangyuewz@163.com | ||
| Webmaster |
Sometimes called the "squeegee effect," it is common to have reverse color friction ridge detail (or footwear impression detail) when the impression matrix is blood. As you have observed, dark colored liquid "squeegees" into the furrows leaving light colored ridge detail. Were the liquid light colored like milk of magnesia and the substrate dark, you could end up with the squeegee effect producing dark colored ridge detail. Of course, viscosity and other factors will give varied results... but it is a pretty common effect. It is also not uncommon to have only part of the ridge detail (or sole design) represented in reverse color, and other portions of the same impression represented as dark (without the squeegee effect) due to normal transfer in an area lacking sufficient liquid to produce the squeegee effect. | ||
| t.w.blankenship |
Does anyone know of any source of information on bloody fingerprints? I've worked two cases and both latents have reversed ridge detail. Instead of seeing the ridge detail, you're actualy looking at the furrows, due to the way the blood is forced down into the furrows from pressure on the finger tips, when making contact with a surface. I've had to reverse the negatives, in-order to get the right colorfor dark ridge detail. Anyone else worked on this problem? Like to hear from you. Officer T. W. Blankenship 309 3rd street, S.w. Roanoke, Va. 24011 |
