If the case is one involving decomposition, the operator is confronted with the problem of dealing with flesh which is rotted or putrefied. The flesh may be soft or flabby and very fragile. If this is so, an examination is made of the finger tips to see if the outer skin is present. If the outer skin is present and intact, it may be possible, using extreme care, to ink and print in the regular manner. Sometimes, the outer skin, although present, will be too soft and fragile to ink and roll in the regular way. In such cases, when the ridge detail is discernible, the skin, if it is easily removed from the finger, or the finger itself may be cut off at the second joint and placed in a 10- to 15-percent solution of formaldehyde for approximately an hour to harden it. Skin placed in a formaldehyde solution usually turns a grayish white and becomes firm. However, it will be brittle and may split if not handled carefully. The skin is placed in the solution only until it hardens sufficiently, after which it is removed and carefully wiped dry with a piece of cloth. Then the skin, placed over the operator's own thumb or index finger and held in place by his other hand, is inked and rolled as though the operator were printing his own finger. If a legible print is not obtainable in this manner, the operator should examine the underside of the skin.
In many instances, where the ridge detail on the outer surface has been destroyed or is not discernible, the ridge detail is clearly visible on the underside (fig. 394). If this is the case, the skin is inverted (turned inside out) very carefully to prevent splitting or breaking and then is inked and printed in the usual way. It must be borne in mind, however, that when the underside of the skin is printed the resulting impression will be in reverse color and position; that is, the ink is actually adhering to what would be furrows of the pattern when viewed from the proper or outer side. If it is deemed inadvisable to try to invert or turn the skin inside out for fear of damaging it, a photograph of the inner ridge detail is made and the negative is printed to give an "as is" position photograph for proper classification and comparison purposes. In order to secure good photographs of the ridge detail it may be advisable to trim the skin, flatten it out between two pieces of glass, and photograph it in that position (fig. 395).
[Figs. 394-395]
When the entire finger is placed in the solution during the hardening process, the skin, in absorbing the formalin solution, may swell and come loose from the finger. Should this occur, the skin must be removed carefully and the procedure outlined above followed. If, however, the skin still adheres to the finger and is not too wrinkled, ink is applied and prints made. Should the skin be too wrinkled to secure a satisfactory impression, consideration is given to the injection of the tissue builder under the skin as previously mentioned, in order to distend the pattern area. If successful, the finger is inked and printed. This, of course, can be done only when the skin is intact.
Should part of the skin be destroyed to the extent that tissue builder cannot be injected effectively, while examination discloses that the pattern area is present but wrinkled, cut off the entire pattern area from the joint to the tip of the finger (fig. 396). Care must be exercised to insure getting the complete fingerprint pattern as well as cutting deep enough to avoid injury to the skin.
[Fig. 396]
After excision, the flesh is carefully and meticulously removed from the inside by scraping, cutting, and trimming until only the skin remains, or until the specimen is so thin it can be flattened out to remove most of the wrinkles. If the skin is fairly pliable, the operator should attempt to place it over one of his own fingers and try several prints. If the prints secured are not suitable, the piece of skin (exert care to avoid breaking or splitting) is flattened out between two pieces of glass and photographed (figs. 397, 398, 399).