T  H  E      D  E  T  A  I  L

The Detail Archives

Discuss This Issue

Subscribe to The Detail


Monday, December  9, 2002

BREAKING NEWz you can UzE...
compiled by Jon Stimac

Triplets Fooled Russia's Prison System - BBC NEWS - Dec. 3, 2002 ...comparison of  the brothers fingerprints finally catch the mix-up...

Arrest Made in 32-year-old Murder - NEWSDAY.COM - Dec. 4, 2002 ...fingerprints and new computers may have helped authorities solve the murder of a cab driver in N.Y., more than three decades ago...

Why Brinks Suspect Got Out - SAN FRANCISCO CHRONICLE - Dec. 5, 2002 ...police had a fingerprint -- but nothing else -- to connect a suspect in last month's fatal California bank holdup...

Hi-Tech Gizmos to Watch Cops - NEW YORK DAILY NEWS - Dec. 5, 2002 ...NYPD will begin using fingerprint scanners to screen the thousands of cops and civilians who go in and out of Police Headquarters daily...

Fingerprinting Raises Privacy Concerns - HR DAILY NEWS - Dec. 6, 2002 ... civil libertarians are saying that there aren’t enough legal protections against abuse...

Good morning via the "Detail," a weekly e-mail newsletter that greets latent print examiners around the globe every Monday morning. The purpose of the Detail is to help keep you informed of the current state of affairs in the latent print community, to provide an avenue to circulate original fingerprint-related articles, and to announce important events as they happen in our field.

Last week,
Glenn Langenburg presented the result of hours of work in making available the Mitchell transcripts on CLPEX.com.  They are available on the "Reference" page, hosted by Glenn himself.  He is still looking for more information (and will probably always be), so keep Glenn in mind if you come across something for his page.  We are exploring the option of purchasing more server space to host even more valuable information, so that is a possibility in the near future.  Maybe Santa will bring us another 100 megs for Christmas.  :)

Last week, I received an e-mail that confirmed that I need to do something I have considered doing for quite some time.  Some of you may have noticed that the CLPEX guestbook has been infiltrated by deviants posting links to porn sites, insurance sites, etc...  Every time one of those posts would appear, it would infuriate me, but I would dismiss it as the "bad" that inevitably comes with the good.  However, lately the problem has significantly increased to weekly, sometimes two or three such posts a week.  Unfortunately, the guestbook is not one I can modify or delete messages from, which had left me in the precarious situation of either continuing to put up with porn links from my guestbook, or to cancel the service and lose all the wonderful entries placed by friends and colleagues from day 1 of the website.  A recent incident reinforced why it must be option 2.  A fellow colleague followed a link from "Adam" who said "Great site" and found themselves viewing pornographic pictures at work.  This prompted justification to the system administrator, who suggested blocking my website from their agency servers.  Naturally, this is not the reputation I want for my site, and I am sure you now understand why I had to move on to a guestbook I can modify and delete messages from.  SO... when you click on "Guestbook" from the CLPEX home page, you now are taken to a nifty new CLPEX guestbook that will forever more remain free from the ravages of deviants.  If you signed the first one, please feel free to sign the new one also.

This week, John Nielson submits an article he wrote for a state IAI division newsletter about 10 years ago, entitled "Rebutting the 'No Fingerprint' Defense."  The timing was perfect for me; last week I had my own "no prints" testimony, and we all know this issue is still just as relevant today as it was 10 or 20 years ago.


Rebutting the "No Fingerprint" Defense
John P. Nielson

the absence of evidence
is not evidence of absence

Fingerprints are accorded a degree respect almost unequaled among all other forms of physical evidence. A fingerprint at the scene or on an instrument of a crime stands as a witness against its donor. [for the sake of brevity, the term fingerprint is used throughout this article. Identifications based upon any area of friction ridge skin (palm, sole or toe, as well as the finger) are equally valid and reliable. [4-5] The term fingerprint should be considered to be synonymous with friction ridge skin. Fingerprint, in its popular usage assumes this metonymy [6] (e.g., a Fingerprint Examiner also compares palm and foot prints).] Unless its presence is consistent with prior or legitimate access, the donor faces a prospect of overcoming that witness in court. A text on the technique of cross-examination acknowledges: "Fingerprints can constitute strong inculpatory evidence. In many instances, your ability to cross-examine the fingerprint expert effectively will greatly influence the jury’s assessment of your client’s guilt or innocence. ... The testimony of the fingerprint expert can be devastating." [1]

Because of this high regard, efforts are sometimes made to equate the certainty of a fingerprint identification with unrelated fields and purposes. DNA profiling seeks to narrow the universe of possible donors of a biological sample to one in millions, with the future goal of being able to individualize the sample to a specific donor. While the present state of the art does not yet allow individualization in forensic cases, the term DNA fingerprinting has been used by some in an effort to create that impression.

A more pernicious misuse of this esteem occurs within the field of fingerprint identification.  The public expects that fingerprints of the perpetrator will be found-an expectation that is probably shaped by television and popular fiction. [2] As a result, an effort is made to attach the same degree of significance to absence of fingerprints as is attached to their presence. 

Just such a situation prompted a 1983 article. [3] In that case, the defense called a private examiner to the stand during a rape trial. No fingerprint evidence had been introduced by the state. Through carefully constructed questioning the impression was created that since prints of the defendant were not found, he had not been present and was therefore wrongly charged. In this case, the examiner was a willing participant in the ruse. 

Examiners working on behalf of the state have been similarly misused. The author, for instance, has been subpoenaed by the defense to testify in cases where prints were developed but none could be linked to the defendant. Through a series of carefully worded questions and controlled answers the lack of prints is painted as exculpatory evidence, creating the inference that the defendant is innocent.

An objective person must concede that the possibility of wrongful charging is sometimes conceivable. However, seeking support for that contention from the lack of fingerprint evidence is clearly erroneous. If the "no fingerprint" defense is raised, adequate cross-examination is required to expose the logical fallacy involved. The relevance and materiality of the lack of evidence must be placed in proper perspective.

Attempts to attach significance to the lack of prints are generally framed in the following manner:

Given fact: no fingerprints belonging to the defendant were found at the scene
Inference: the defendant was not at the scene

In order for the inference to be true, at least three presuppositions must each be true. If any of the presuppositions are false, then the inference is false:

1. Everywhere the defendant goes, the defendant leaves fingerprints.
2. Everywhere the defendant leaves fingerprints, the fingerprints will be found.
3. The fingerprints the defendant leaves will be of sufficient quality to be identifiable.

Presupposition 1

If the inference is true and you can tell where the defendant has not been because of the absence of fingerprints, then it must logically follow that anywhere the defendant goes, he must leave fingerprints. If the defense will not accept this counter-construction, their argument is invalidated, for the only way it can be said that the lack of prints proves (or tends to prove) absence is that the defendant leaves prints everywhere he goes as proof of presence. If there is even one place the defendant has been and not left prints (and every time he was there), the presupposition is invalid.

Arguing from the general to the specific it can also be inferred with a high degree of confidence that if the premise fails in the general case it will also fail in the specific case in the absence of contrary proof. Such contrary proof is impossible to demonstrate since it would require the accumulation of data for the time of the individual’s birth to show unerring uniformity.

Latent prints will not necessarily be recovered in every instance. [7-8] Broad classes of reasons can be put forth as examples of occasions when fingerprints may not be left when the person was, in fact, present. Although there are others, [9-10] three categories will be considered: physical barriers, transfer interferences and physiological factors.

1. Physical Barriers The soles of the feet and toes, like the palms and fingers, contain friction ridges arranged in patterns that can be individualized. Why are identifications made from footprints relatively rare, though no less sure? To a large measure, it is because a barrier (shoes and socks) normally exists between foot and floor.

Since unique and identifiable patterns are capable of being left everywhere the defendant walks, shall we conclude that because we do not find the defendant’s footprints, he has not been at a certain spot? Even if there is an eyewitness to his presence, shall we deny the witness’ statement on the basis of the lack of a footprint? For no less valid reason do we fail to leave fingerprints when a barrier is placed between fingers and the surface handled.

This barrier can take many forms: gloves, a handkerchief-anything that prevents direct contact between the hand and the surface touched. Has the defendant never worn gloves? On even the most bitter cold morn? If he has worn gloves even once, then he has been somewhere he didn’t leave fingerprints at least during the time he was wearing gloves. The same question can be posed regarding other barriers and other times.

2. Transfer Interferences Even when a barrier is not purposely interposed, a latent print may not be deposited. Both depositing surface interferences and accepting surface interferences may be involved. 

Depositing surface interferences include any contaminant on the friction ridges which hinders or prevents the deposit of fingerprint residue. For instance, dirt, grease, and other foreign matter can obliterate the fine detail which must be present to effect an identification.  In the extreme case, most people have seen the impressions left by a finger caked with dirty grease from an automobile engine. To some greater or lesser extent, the same type of situation takes place whenever foreign matter is present on friction ridge skin.

Accepting surface interferences include the same types of foreign matter: dust can completely soak up perspiration and oils, caking to the finger as it is removed from the surface; a light film of grease or oil can be sufficient to obliterate fingerprints when processed by most means. Molded or machined plastics for household use are often coated with an oil or silicone mold release agent when purchased.

Objects that are damp or wet will often fail to accept latent prints. A commonly encountered example is a beverage bottle or can which, when cold, “sweats” (condenses water on the surface).

The composition of the accepting surface can hinder or frustrate attempts to recover usable prints. Objects that are extremely porous or are made using course fibers prove to be poor receiving surfaces. Some materials display an electrostatic charge, causing fingerprint powders to adhere without differential preference.

Surface texture also plays an important part in allowing successful transference. If the surface is uneven, only partial transfer will result leaving a print which is of no real value for identification. If the surface is rough, fingerprint powder may become trapped in the recesses causing such a loss of contrast as to obscure latent impressions. In addition, a rough surface may induce a capillary effect, diffusing the deposit.

3. Physiological Factors There are a number of conditions which can interfere with the ability to leave fingerprints. Low temperatures cause sweat pores to constrict, lessening perspiration and therefore the likelihood of transfer. Mental and emotional state often have physiological manifestations. Illness (temporary or chronic), certain drugs and inherited tendencies may all cause secretions to be diminished to such a level that no significant transfer takes place.

Any Examiner or Crime Scene Technician with even a modicum of tenure has examined items which have been handled on which no fingerprints were subsequently found. Be the reason a barrier of some sort, a multiplicity of possible transfer interferences, freshly washed and dried hands, natural tendencies to secrete low levels of certain substances, or a cold environment, the result is the same.

Presupposition 2

If the inference presented above is true, then not only must the defendant leave fingerprints, we must conclude that they will be found by law enforcement. If the defendant leaves fingerprints but they are not found, a false conclusion will be reached: since no fingerprints belonging to the defendant were identified, the defendant was not present.

To enforce this presupposition, a burden is placed on the state-the burden of omniscience.  Assuming even one fingerprint is left, the investigating agency must have the perception to know where to look. Areas reasonably believed to have been transgressed are examined during a thorough crime scene investigation. The crime scene investigator cannot be expected to divine the offender’s every step through the scene, however.

Investigators must also be imbued with infallibility, for if the one print is found, it must be preserved and processed in such a way as to keep it from destruction. Although protocols have been established to maximize the probability of recovery of prints, no one technique yields identical results in all circumstances. Some processing techniques remove or alter constituents of print residue which could be used to conduct additional examinations. The choice of a method thought to be useful in that particular circumstance might not yield usable prints and at the same time negate the possibility of further productive examinations. [11] 

If allowed to stand, this presupposition would place upon the state a burden unequaled in the scope of evidentiary procedure. If, because fingerprints of a particular suspect were not found that suspect could be excluded, then it would follow that if no fingerprints were found no prosecution could take place, for no one committed a crime. (If someone had, fingerprints would have been found.) Such a conclusion is obviously and patently false.

Presupposition 3

Finally, if the inference is true, not only must the defendant leave fingerprints which are found, but those fingerprints must be of sufficient quality to yield an identification. While this is a technical issue which many assume in their definition of “fingerprint,” it is a constant consideration to those who work in the field. The term “identification” as used here describes a conclusion at the level of moral or scientific certainty made by the examiner; a conclusion that the crime scene print was made by the same finger as the known print recorded from the suspect.

Crime scene prints are unintentional, chance prints for which there is no thought (or desire) to produce a clear reproduction. The resultant problem is that too few details are clearly enough reproduced to enable an identification. Transfer considerations aside, movement of the finger by a distance equal to the width of one furrow between ridges (1 to 2/100ths of an inch) is sufficient to blur a print beyond use. Besides blurring due to rotational, lateral, or longitudinal movement, deformation of the finger as it presses firmly against a surface typically causes some distortion and edge blurring. An insufficient reproduction of detail occurs when only a small section of the ridge pattern is transferred, even without blurring- such as when an item is handled by the tips or sides of the fingers using light pressure.

A significant percentage of all prints developed during crime scene and latent print examinations fall into these categories: smearing that reminds one of a child’s finger painting; small fragments of ridged skin impressions with too few details to make the print of value for identification; edge blurring or pressure distortion; fingerprints deposited while the surface or hand was moving causing slippage and resulting in only partial clarity; overlapping prints that obscure details in each print; transfer interferences and other variables. All combine to make identifiable crime scene fingerprints truly chance impressions. [12]

Tables I and II display data gleaned from several sources. While there are differences in year of report and format, several facts emerge: on average only 45% of the scenes processed yielded identifiable prints. A significant number of those prints can be attributed to persons having legitimate access (family, friends, owners, customers, guests-even to the suspect if there is a possibility of deposit during a period of legitimate access). The mean (average) rate of suspect identifications is only three scenes in one hundred. (these results were published prior to the availability of Automated Fingerprint Identification Systems (AFIS).
Lacking AFIS, an agency usually requires that a suspect be named before a comparison can be attempted; few agencies “ cold search” their fingerprint card files excepting extraordinary circumstances.  With the advent of AFIS, the individual inked fingerprint images are stored in computerized form and crime scene prints are scanned against this database. Inked fingerprints containing ridge detail which most closely approximates the search print are then presented for comparison.  Agencies report AFIS match rates of 7 to 25%. These numbers are inflated, however, in the sense that agencies often require that latent prints be first compared with “ elimination” inked fingerprints to cull out as many non-suspect prints as possible. The resultant “ hit” (identification) rate is expressed as a percentage of cases entered into AFIS, not as a percentage of total scenes.)

Table 1
Productivity of Crime Scene Processing for Fingerprints
Residential Burglary Sample [13]
[200 randomly selected residential burglary cases from each department (cleared or uncleared)]

  Long Beach, CA

Berkeley, CA

Richmond, CA
% cases in which crime scene
technicians were requested
58.0 76.6 87.6
% of tech. requested cases
where prints were recovered
50.8 42.0 69.1
Cases where prints were
recovered, as % of total cases
29.4 32.2 60.5
Cases in which a suspect was
identified as the result of latents, as % of total cases
1.5 1.1 1.2

Table II
Success Rates in Recovering Identifiable Latent Prints and in Making Identifications [13-16] [population figures are rounded, from census information: 1970 (Los Angeles, Washington, Miami, Richmond) or 1980 (Portland, Kalamazoo), and scenes per year are rounded figures]

  Los Angeles, CA Washington, D.C. Portland, OR Miami, FL Kalamazoo, MI Richmond, CA
Population  2,812,000 757,000 368,000 335,000 80,000 79,000
Scenes/yr. 28,000 33,800  9,000 8,700 2,300 4,000
Scenes with
usable prints/
total scenes
processed (%) 
50% 42% 25% 48% 16% 70%
# scenes
yielding latents
that are ident/
total scenes
processed (%)
4.6% 1.8% 4.4% 4.4%  2.2%  6.9%

As stated above, if any one of the three presuppositions fail, the conclusion must fail. In the general case, each of the presuppositions have flaws. Some are fatal.

Beyond such proofs, however, one should consider that advancing the contention that the lack of fingerprints “proves” that the defendant did not commit the offense is as unfounded as a contention that because there were prints that were smeared beyond value, the defendant must have been present. Both contentions are based upon an argument from silence. Each uses fallacious reasoning in an attempt to support a position without respect for the reasonable conclusions that can be drawn from the available facts. 

Neither conclusion advances the cause of justice or the proof of fact.

[The desire to use an argument from silence is not the exclusive domain of the defense. Consider the following report of one such exchange: In a robbery case the victim, a bartender, testifies that the defendant had come into the tavern earlier in the night for a glass of beer. Three unwashed glasses were found at the scene and were processed for latent prints. Two of the glasses yielded prints, but these were from persons unknown, not the defendant. The prosecutor suggests that the print examiner testify that the third beer glass must have been used and wiped clean by the defendant, because the other two glasses were obviously not his. The print examiner suggests that the prosecutor look elsewhere for this kind of testimony. The prosecutor looks surprised. [17] An examiner’ s ethical responsibility is to the facts and the logically supportable conclusions they will sustain, not to the theory of prosecution or defense. Identifications are based upon “a reasonable degree of scientific certainty.” Testimony as to possible or probable identifications are grounds for disciplinary measures against members by sanctioning organizations. Unless clearly elicited by the examining attorney and well qualified during testimony, such statements transgress the bounds of ethical conduct. [18]

For further information, contact:
John P. Nielson
State Crime Lab - Milwaukee
1578 South 11th Street
Milwaukee, WI 53204
(414) 382-7500
fax: (414) 382-7507
e-mail: nielsonjp@doj.state.wi.us <mailto:nielsonjp@doj.state.wi.us>

[John Nielson began his law enforcement career in 1973 with the Johnson County Sheriff’s Office, in
Iowa City, Iowa. From 1977 to 1983, he was a Detective and Identification Officer. Since 1983, Mr.
Nielson has been employed as a Forensic Scientist and, most recently, as a Forensic Scientist Supervisor by the State Crime Lab in Milwaukee, Wisconsin. He has been a Certified Latent Print Examiner since 1981. This is a revision of an article which appeared in 1983, prepared in 1993 at the request of a state division IAI newsletter editor, and recently submitted for consideration in the Weekly Detail.]

[1] Bailey, F.L. and Rothblatt, H.B, Cross-Examination in Criminal Trials, Bancroft-Whitney, San Francisco, 1978, p. 256.
[2] Imwinkelried, E.J., Methods of Attacking Scientific Evidence, Michie, Charlottesville, VA, 1982, p. 2.
[3] Nielson, J.P., “A Rebuttal to the ‘No Fingerprint’ Defe Identification News, 33 (8), August 1983, pp 12-13.
[4] Moenssens, A.A., Inbau, F.E., and Starrs, J.E, Scientific Evidence in Criminal cases (3rd Ed.), Foundation Press, Mineola, NY, 1986, pp. 447-48.
[5] Moenssens, A.A., Fingerprints and the Law, Chilton, Philadelphia, 1969, pp. 135-138.
[6] Peña, M.S., Practical Criminal Investigation, (2nd rev ed), Custom, Placerville, CA, 1990, p. 105.
[7] Olsen, R.D., Sr., Scott’s Fingerprint Mechanics, C.C. Thomas, Springfield, 1978, p. 117.
[8] Osterberg, J.W., The Crime Laboratory, Indiana U. Press, Bloomington, 1968, pp. 24.
[9] Olsen, R.D., Sr., Scott’s Fingerprint Mechanics, C.C. Thomas, Springfield, 1978, pp. 117-122.
[10] Osterberg, J.W., The Crime Laboratory, Indiana U. Press, Bloomington, 1968, pp. 24-28.
[11] Cowger, J.F., Friction Ridge Skin, Elsevier, New York, 1983, pp. 76-77.
[12] Moenssens, A.A., Fingerprint Techniques, Chilton, Philadelphia, 1971, p. 104.
[13] Petersilia, J.R., “Processing for Latent Prints - What are the Payoffs?,” J. Police Science and Administration, 6 (2), June 1978, pp. 157-167.
[14] Conner, D.L. “More On ‘The Philosophy of the Field of Identification’,” Identification News, 32 (9), September 1982, p. 13.
[15] Cushman, B.Q., “Comments On: ‘The Philosophy of the Field of Identification’,” Identification News, 32 (6), June 1982, pp. 13, 15.
[16] Cushman, B.Q., unpublished data.
[17] Garrison, Jr. D.H., “Bad Science,” M.A.F.S. Newsletter, October 1991, pp. 11-23
[18] “Resolution VII Amended,” Identification News, 30 (8), August 1980, p. 3.


For more reading on this subject, read over "The Importance Of The Lack of Fingerprints - A Challenge To The Prosecution," at http://www.scafo.org/library/110302.html

To discuss this week's Detail, visit the informal CLPEX.com message board at
As usual, the onin.com forum (http://onin.com/fp/wwwbd/) is also available for more formal latent print-related discussions.

Next week, we are playing it by ear again.  If you have something to submit, I'm just an e-mail away at kaseywertheim@aol.com.


UPDATES on CLPEX.com this week...

No major updates on the site this week.

Feel free to pass The Detail along to other examiners.  This is a free service FOR latent print examiners, BY latent print examiners. There are no copyrights on The Detail, and the website is open for all to visit.

If you have not yet signed up to receive the Weekly Detail in YOUR e-mail inbox, go ahead and join the list now so you don't miss out!  (To join this free e-mail newsletter, send a blank e-mail to: theweeklydetail-subscribe@topica.email-publisher.com )  Members may unsubscribe at any time.  If you have difficulties with the sign-up process or have been inadvertently removed from the list, e-mail me personally at kaseywertheim@aol.com and I will work things out.

Until next Monday morning, don't work too hard or too little.

Have a GREAT week!