Fingerprints

The search for latent prints is done in a systematic andintelligent manner. Investigators develop techniques to locatetraces of fingerprints at a crime scene. The basic premise insearching for latent prints is to examine more carefully thoseareas, which would most likely be touched by persons who havebeen on the scene. The natural manner in which a person woulduse and place his hands in making an entrance or exit from abuilding or in handling any object is the key to the discovery oflatent prints.

Where a forced entrance has been made, latent prints are likely to be found on any surfaceadjacent to or at that point. Any object with a smooth, non-porous surface is likely to retain latentprints if touched. Fingerprints on rough surfaces are usually of little value. If the fingermark doesnot disclose ridge detail when viewed under a reading glass, the chances are that its value inidentification is nil when photographed. Where fingermarks are found, it will be necessary for theinvestigator to compare them against the ones of persons having legitimate access to the premisesso that the traces might be eliminated as having evidentiary value if they prove to be from thesepersons. Places to search for prints on an automobile are the rear view mirror, steering wheel hub,steering column, windshield dashboard and the like.

Dusting of surface may be done with a fine brush or with an atomizer. The whit powders usedare basically finely powdered white lead, talc, or chalk. Another light powder is basically Chemist’sgray. A good black powder is composed of lampblack, graphite, and powdered acacia. Dragon’sblood is good powder for white surface and can be fixed on paper by heating. In developing latentprints, the accepted method is to use the powder sparingly and brush lightly. Do not use powder ifthe fingermark is visible under oblique lighting. It can be photographed. A good policy for thenovice is to experiment with his own prints on a surface similar to the one he wishes to search inorder to determine the powder best suited to the surface. Fingerprints after dusting may be liftedby using fresh cellulose tape or commercially prepared material especially designed to lift andtransfer dusted latent fingerprints.

In addition to latent prints, the investigator must not overlook the possibility of two other typesof fingerprint traces: molded impression and visible impression. Molded impressions are formed bythe pressure of the finger upon comparatively soft, pliable, or plastic surfaces producing an actualmold of the fingerprint pattern. These can be recorded by photograph without treating thesurface, is usually most effective in revealing the impressions clearly. Visible impressions are formedwhen the finger is covered with some substance which is transferred to the surface contacted.Fingers smeared with blood, grease, dirt, paint, and the like will leave a visible impression. If theseimpressions are clear and sharp, they are photographed under light without ant treatment.Ordinarily, prints of this type are blurred or smeared and do not contain enough detail foridentification by comparison. However, they can not be overlooked or brushed aside without firstbeing examined carefully.

1. What is the best title for this passage?
[A] Visible impressions. [B] Moulded impressions.
[C] Fingerprints. ? ? ? ? ? [D] Latent fingerprints.

2. How many fingermarks are mentioned in this passage?
[A] 2. [B] 3. [C] 4. [D] 5.

3. Which type of fingerprints is most likely to retain?
[A] Latent fingerprints. ? ?[B] Visible impressions.
[C] Moulded impressions. [D] Clear fingerprints.

4. How many ways are there to develop fingerprints?
[A] 2. [B] 3. [C] 4. [D] 5.

答案詳解（反白可見(jiàn)）：
1. C. 指印，不管哪一種。
A. 可見(jiàn)壓痕。 B. 模性壓痕。 C. 潛指印，都屬于指印。所以最佳的標(biāo)題應(yīng)是指印。
2. B. 三種指印，即：潛指印，模性和可見(jiàn)壓痕。
3. A. 潛指印。因?yàn)闈撝赣‰[秘，又是作案人無(wú)意中留下不易為人發(fā)現(xiàn)和破壞。其價(jià)值性從文中第三段描寫(xiě)取潛指印可見(jiàn)一般。
B. 和C. 見(jiàn)第四段“一定不要忽略其它兩種類(lèi)型的指印痕：模性壓痕和可見(jiàn)壓痕的可能性”這說(shuō)明這兩種指印較少，特別是模性壓痕是在相當(dāng)柔軟，柔韌或者塑性表面留下的，作案人一般都是小心翼翼的，不留下指印，更不太可能在這類(lèi)東西上壓上一個(gè)指痕。至于可見(jiàn)壓痕，是手上沾了“血，油脂，臟土，油漆之類(lèi)物品”留下?！耙话銇?lái)說(shuō)，這種類(lèi)型的指印都是模糊不清或者是污臟難分，比較之下它們對(duì)鑒定來(lái)說(shuō)，沒(méi)有足夠細(xì)節(jié)證據(jù)?！?D. 清楚指印，沒(méi)有這個(gè)專(zhuān)門(mén)名稱(chēng)。
4. A. 兩種。第三段第四句起“在顯影指印時(shí)，公認(rèn)的方法是用少許粉末，輕輕拂掃。如果指印在昏暗的燈光下可見(jiàn)，就可以攝影”，“指印輕掃后就用指紋膠帶或商業(yè)專(zhuān)備材料把它們?nèi)∠?。這是一種專(zhuān)門(mén)設(shè)計(jì)用于取下和轉(zhuǎn)移輕拂掃后的指印材料?！?/span>

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