Have you ever seen this type of bloody handprint, where you can see that a clear handprint is present, but because of background color or texture interference, it is impossible to photograph the handprint clearly, let alone be able to clearly identify the feature points of the handprint? For example, bloody handprints on black sofas, bloody handprints on bed sheets, bloody handprints on dark door panels, bloody handprints on some black plastic boxes or packaging, and so on.

We can see the existence of the mudras, but we can't judge the details of the handprints. Do you feel sorry that such mudras cannot be effectively tested?

status quo

In most cases, technicians take a secondary approach – DNA testing. However, most of these specimens are the victim's blood, which contains only a trace amount of suspect exfoliated cells, so the map obtained by DNA testing is often a single type of the victim, or a classification of suspects with a very low signal, which has little effect on the detection work.

Workaround

So is there nothing that can be done about such bloody handprints encountered in major criminal cases? Of course not, Zar-Pro Blood Handprint Extraction Film is a perfect solution. Regardless of whether the object is permeable or non-permeable, and the background color, Zar-Pro Blood Handprint Extraction Film can successfully extract the blood handprint from the object. Moreover, the sensitivity of the film is very high, and the film that extracts the blood handprint can excite fluorescence under a multi-band light source. The main principle is that the film contains a special chemical formula, which is activated by the activation reagent, binds to proteins or amino acids in the blood, and can be fluoresced by multi-band light source excitation. And the white film background can provide a clean background for the observation of blood handprints.

Some scholars have done detailed research on Zar-Pro blood handprint extraction film, and achieved the desired results, the study used more than 20 kinds of objects including aluminum, black plastic, blue plastic, glass, metal steel sheet, oilcloth, glazed tiles, painted dry walls, brown and black leather, brown and black vinyl resin, human forearm skin, whitewashed concrete, glossy paper, dyed wood, canvas, nylon, denim, cotton, etc. including non-permeable, permeable, semi-permeable and so on. In addition to denim and canvas, which are difficult to distinguish due to the rough background texture and the extracted handprint feature points, the other handprint pattern types and/or ridgeline details can be obtained.

The experimental results are as follows:

A new method of blood handprint enhancement and extraction| the extraction of blood handprints on a black sofa "Hongde Net"

After the completion of the production, the blood handprint is stored for 1 hour, 1 day, 1 week, 1 month, 3 months, 6 months and other different intervals and then extracted to observe the extraction of blood handprints, aluminum, black plastic, metal (non-permeable); dyed wood, black leather (semi-permeable); cotton (permeability) can obtain pattern type and /or) clear ridge line details

Studies have also been conducted on the extraction effect of blood handprints made of 10x, 100x and 1000x dilution of blood. Experiments have shown that blood handprints made of 100 times diluted blood can still be observed after being irradiated by multi-band light sources.

Some of the blood handprint extraction photos are as follows:

Figure 1: Wood: (a) the object after extraction; (b) the blood handprint after extraction

Fig. 2 Brown leather: (a) the object after extraction;

Figure 3 Denim: (a) the object after extraction;

Fig. 4 Cotton (6 months) :(a) Object (normal light) after extraction ;(b) Extracted blood handprint (normal light) ;(c) Extracted blood handprint (multi-band light source)

Fig. 5 Glossy paper (multiband light source) dilutes blood: (a) 0; (b) 1/10; (c) 1/100; (d) 1/1000

The study believes that Zar-Pro blood handprint extraction film has near-universal effectiveness, providing a simple, non-toxic method for extracting and photographing blood handprints from various objects. Fluorescent handprints can be observed under multi-band light source illumination, even when the amount of blood is small and the handprint lines cannot be observed normally under white light conditions on the extracted film. The study also found that on some non-permeable and semi-permeable objects, the white component on the film will be transferred to the object, not only will not destroy or change the handprint on the original object, but also play an enhancing role. In addition, after two years of storing the extracted blood handprints, there is no significant fluorescence attenuation, and fluorescence testing can still be performed.

A new method of blood handprint enhancement and extraction| the extraction of blood handprints on a black sofa "Hongde Net"

status quo

Workaround