Michele Triplett's Fingerprint Terms ©
A collection of over 1000 terms used in the Science of Fingerprint Identification.

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R. v. Mohan (1994)
On appeal to the Supreme Court of Canada from the Ontario Court of Appeal, a decision on the 
admissibility of expert evidence and the nature of expert evidence and how it pertains to 
disposition.  A Canadian decision similar to the American Daubert Hearings, the Mohan decision 
has set the parameters and application for the admission of expert in Canada.

Admission of expert evidence depends on the application of the following criteria:
a)  Relevance
b)  Necessity in assisting the trier of fact (judge or jury)
c)  The absence of exclusionary rule
d)  Must be by a properly qualified expert

In R. v. Mohan, four counts of sexual assault on female patients ages 13-16 were laid against a 
practicing paediatrician.  His counsel indicated that he intended to call a psychiatrist who 
would testify that the perpetrator of the alleged offences would be part of a limited and 
unusual group of individuals and that the accused did not fall within that narrow class 
because he did not possess the characteristics of the group (profile) however the evidence 
was ruled inadmissible.

The original conviction was stayed by the Court of Appeals and opened a new hearing.  
At issue was the determination of the circumstances in which expert evidence is admissible 
to show that the character traits of an accused person do not fit the psychological profile 
of the putative perpetrator of the offences charged.  The resolution of the issue involved 
the examination of the rules relating to (i) expert evidence, and (ii) character evidence.

In summary, expert evidence which advances a novel scientific theory or technique is 
subjected to special scrutiny to determine whether it meets a basic threshold of reliability 
and whether it is essential in the sense that the trier of fact will be unable to come to a 
satisfactory conclusion without the assistance of the expert.

The Supreme Court allowed the appeal but decided that the evidence should be excluded 
as nothing in the court record supported a finding that the profile of a paedophile or 
psychopath (as alleged by the psychologist) has been standardized to the extent that it 
could be said that it matched the supposed profile of the offender depicted in the charges.  
The expert’s group profiles were not seen as sufficiently reliable to be considered helpful.
http://www.canlii.org/en/ca/scc/doc/1994/1994canlii80/1994canlii80.pdf 8-1-2009
Courtesy of Cst. Jonathan BALTZER and Sgt. Tim Walker, RCMP

RAM
Combination of Rhodamine 6G, Ardrox and MBD dyes, which fluoresce 
when exposed to selected wavelengths of light; used to visualize 
cyanoacrylate fumed friction ridge detail.
SWGFAST, Glossary - Consolidated 09-09-03 ver. 1.0
http://www.swgfast.org/Glossary_Consolidated_ver_1.pdf

Developed in 1990 by four FBI Latent Print Examiners: Harless Cummins, 
Felix Peigare, Mitchell Hollars and Tim Trozzi.

RAY
A fluorescent dye stain (a combination of Rhodamine 6G, Ardrox, and 
Basic Yellow 40) used to visualize cyanoacrylate ester fumed friction 
ridge detail.   Optimum viewing is done with an alternate light source 
(450-550nm) and orange or red goggles. 

R6G
See Rhodamine 6G.

RTX
See Ruthenium Tetroxide.

RUVIS
Reflective Ultra-Violet imaging system that allows visualization of friction 
ridge detail in the ultraviolet spectrum.
SWGFAST, Glossary - Consolidated 09-09-03 ver. 1.0
http://www.swgfast.org/Glossary_Consolidated_ver_1.pdf

Radial
The smaller of the two bones of the forearm, on the same side as 
the thumb.
SWGFAST, Glossary - Consolidated 09-09-03 ver. 1.0
http://www.swgfast.org/Glossary_Consolidated_ver_1.pdf

Radial Longitudinal Crease
The crease that encloses the thenar area and interdigital pad 1.  
Below the proximal transverse crease.  Known as the 'line of life'.

Sampling
See Sampling.

Rarity
Fewness or scarcity of an item, thing, or shape.
Quantitative-Qualitative Friction Ridge Analysis, David R. Ashbaugh 1999 CRC Press

Reagent
Substance used in a chemical reaction to detect, examine, measure, or 
produce other substances.
SWGFAST, Glossary - Consolidated 09-09-03 ver. 1.0
http://www.swgfast.org/Glossary_Consolidated_ver_1.pdf

Red Flags
Danger signs, common in latent fingerprints that may indicate a 
distortion in the ridge path.
Quantitative-Qualitative Friction Ridge Analysis, David R. Ashbaugh 1999 CRC Press

Redox
Reduction-Oxidation.  Chemical reaction in which one or more electrons 
are transferred from one atom or molecule to another.  An important 
component of the Physical Developer and Multimetal Deposition processes.
SWGFAST, Glossary - Consolidated 09-09-03 ver. 1.0
http://www.swgfast.org/Glossary_Consolidated_ver_1.pdf

Redwop ™
A fluorescent fingerprint powder developed by Ed German in 1986 and given to the 
Lightning Powder Company.

In the mid-1980’s, Brent Cutro, with the Illinois State Police, noticed the paint 
pigment on an Oxydol box glowed under certain light wavelengths.  Ed German researched 
this phenomenon and found it was a substance known as Fire Orange pigment. He then 
established the optimal dilution of Fire Orange pigment in lycopodium to effectively 
dust for latent prints.  This was the first latent print development powder tailored 
for blue-green wavelength excitation.  Ed German gave his new invention to Lightning 
Powder Co. Michael Carrick, of Lightning Powder, named the new invention Redwop. The 
components of Redwop may have changed since its inception. 

Redwop (powder spelled backwards) is a very fine fluorescent powder.  It is especially 
useful on multicolored objects but also works well on wood and vinyl. A feather or 
zephyr brush is the preferred application. Optimum viewing is done with an alternate 
light source using blue-green excitation (475-510 nm) and an orange filter. When competing 
luminescence occurs with the background/substrate, viewing at 570 nm and a red filter or 
viewing with UV lighting can improve visualization. Yellow goggles should be used to 
protect eyes from UV light. Redwop is non-caustic to the skin but breathing the dust 
particles should be avoided.  

Re-examination
A re-examination is a reassessment of a conclusion(s) which can be done by 
the same individual or a different individual, and done with either the original 
evidence or reproductions of the evidence.  The person doing the 
reassessment may or may not know of the original conclusion(s).  A 
re-examination is different from normal verification (although it can verify 
the conclusion) because the intent of re-examination may be different.  
The intent of re-examination is to check if other conclusion can also be 
determined while the intent of verification is to check the reliability of 
the conclusion(s).  Differing conclusions may arise due to the differing 
information.

Reh, Dr. Ludwig (1894)
Dr. L. Reh was an early researcher on the hands and feet of mammals.  Reh 
classified many of the various epidermic formations as scales but separated 
the fine lines that covered the pads.  He wrote "Die Schuppen 
der Saugetiere" ("The Scales of Mammals") in 1894 where he stated that ridges 
did not evolve from scales, they are of secondary origin.

Reis, George
George Reis is one of the early users of digital imaging in forensics and is a 
knowledgeable and prominent forensic imaging expert in the United States.

Mr. Reis started his career as a photographer, photojournalist and photo lab 
technician.  From 1989 to 2004 he worked for the Newport Beach Police Department 
in California as a forensic photographer.  In 1991 he began experimenting with 
digital imaging technology and the following year NBPD started using this 
technology for fingerprint analysis.  

In 1995, George Reis founded Imaging Forensics, which provides training and 
consulting services in both digital imaging and photography.  Through his company 
he has trained personnel from the Secret Service, FBI, US Army Crime Lab, state, 
county and municipal agencies.  In addition to training, Imaging Forensics provides 
consulting to police agencies in order to help them transition to digital imaging 
technology.  They also provide litigation support on criminal and civil cases (for 
both plaintiff and defense).  

Mr. Reis is certified by the IAI in Forensic Photography. He is a member of the 
Forensic Photography and Imaging Certification Board, and a member of the Journal 
of Forensic Identification editorial review board.   Additionally, Mr. Reis is an 
alpha and beta tester for Adobe Photoshop.

Relative Position
Proximity of characteristics to each other.
SWGFAST, Glossary - Consolidated 09-09-03 ver. 1.0
http://www.swgfast.org/Glossary_Consolidated_ver_1.pdf

Reliable
The ability for a technique to produce consistent results. 

Renoe, Alexander J. (A. J.)  (1868-1939)
Renoe was a prominent United States identification expert in the early 
1900's.  He learned about personal identification from Capt. Michael P. 
Evans.  In 1889, while working at the Illinois State Reformatory, Renoe 
was asked to organize a Bertillon identification unit for the reformatory.  
In 1904, he added a fingerprints system.  In 1908, he was asked to implement 
a finger print system for the Minnesota State Penitentiary.  Just a few 
months after this he was offered the position of records clerk for the US 
Penitentiary at Leavenworth, Kansas under the Warden, Major R. W. McClaughry.  
In 1914, he was appointed Chief of the Bureau of Identification for the US 
Department of Justice, which was located at Leavenworth.  While working in 
this position, Renoe developed the extensions to the Henry System that were 
used by many police departments, including the FBI.  He held this position 
until 1923 when this finger print section was combined with the National 
Police Bureau's records to form the Identification Section of the Federal 
Bureau of Identification in Washington D.C.  Renoe was appointed technical 
expert in the reorganization.  Among his other accomplishments, in 1921 Renoe 
was elected as the 2nd president of the IAI and served two terms in this position.

Repeatable
The ability for a technique to produce consistent results by a single person.

Reproducible
The ability for a technique to produce consistent results by others.

Accuracy-extended to which a measurement agrees with the accepted 
or correct value.
www.esb.utexas.edu/dbm/Teach/bot308/Unit1/02science.htm

Reticular Layer
One of the two layers of the dermis.  The layer that is furthest 
from the epidermis.

Reversed Image
See Image Reversal.

Reversed Color or Tones of Print
See Tonal Reversal.

Reviews, types of
Administrative Review
Peer Review
Technical Review
Verification can be used as either a review process or a re-examination process

Reyes, Victor
See State of Florida vs. Victor Reyes.

Rhodamine(s)
Family of dyes that produce fluorescence when exposed to selected 
wavelengths of light; used to visualize cyanoacrylate fumed friction 
ridge detail.
SWGFAST, Glossary - Consolidated 09-09-03 ver. 1.0
http://www.swgfast.org/Glossary_Consolidated_ver_1.pdf

Rhodamine 6G
A fluorescent dye stain used with an alternate light source to 
visualize cyanoacrylate ester fumed friction ridge detail.  Optimum 
viewing is done with an alternate light source (495-540nm) and 
orange or red goggles.

Ridge (Friction)
See Friction Ridge.

Ridge Aplasia
Congenital absence of friction ridge skin.
SWGFAST, Glossary - Consolidated 09-09-03 ver. 1.0
http://www.swgfast.org/Glossary_Consolidated_ver_1.pdf

Ridge Characteristics
See Characteristics
SWGFAST, Glossary - Consolidated 09-09-03 ver. 1.0
http://www.swgfast.org/Glossary_Consolidated_ver_1.pdf

Ridge Count
The number of ridges between the core and the delta.  Used in the 
Henry Classification System.

Ridge Detail in Nature
John Berry (Hertfordshire) commenced publication of this esoteric journal in 
1979, dealing with his observations that the seven basic ridge detail 
characteristics appear throughout nature, obvious examples being zebra and 
wind-blown or tidal-formed ridges and furrows on sand surfaces.  In the 
century prior to his research, a dozen or so discoveries had been noted in 
fingerprint publications.  The first issue of RIDGE DETAIL IN NATURE was 
circulated with ‘Fingerprint Whorld’ in 1979, featuring over seventy 
discoveries, many being illustrated.  Since then Berry has published twenty-
five annual issues, many profusely illustrated, and with large page counts.  
The journal was re-titled STRABISMUS in 1998.  At the end of 2004, the total 
of ridge detail discoveries was 1,556.  Alice Maceo, of the Las Vegas Metro 
Police Department, has lectured at I.A.I. conferences, citing many of Berry’s 
reported discoveries, and proffering her theory for the phenomenon.  Berry 
also lectured on the subject at fingerprint conferences in several countries 
before his retirement in 1991.  John Berry expresses his appreciation for the 
reports of over thirty researchers in the last quarter century, especially his 
friends and ex-colleagues at Hertfordshire, Martin Leadbetter and Mike Walker.

Ridge Dissociation
See Dissociated Ridges
SWGFAST, Glossary - Consolidated 09-09-03 ver. 1.0
http://www.swgfast.org/Glossary_Consolidated_ver_1.pdf

Ridge Dysplasia
See Dysplasia
SWGFAST, Glossary - Consolidated 09-09-03 ver. 1.0
http://www.swgfast.org/Glossary_Consolidated_ver_1.pdf

Ridge Flow
1. The direction of one or more friction ridges.
2. A component of Level 1 detail.
SWGFAST, Standard Terminology of Friction Ridge Examination 3-23-11 ver. 3.0

Ridge Hypoplasia
Underdeveloped ridges associated with an excess of creases.
SWGFAST, Glossary - Consolidated 09-09-03 ver. 1.0
http://www.swgfast.org/Glossary_Consolidated_ver_1.pdf

Ridge Path
1. The course of a single friction ridge.
2. A component of Level 2 detail.
SWGFAST, Standard Terminology of Friction Ridge Examination 3-23-11 ver. 3.0

Ridge Unit
A theoretical length to indicate a segment of a friction ridge.  This length is approximately 
the same distance as the width of a friction ridge and signifies the area around one pore.

Small section of a friction ridge containing one pore.
Quantitative-Qualitative Friction Ridge Analysis, David R. Ashbaugh 1999 CRC Press

See Friction Ridge Unit.
SWGFAST, Standard Terminology of Friction Ridge Examination 3-23-11 ver. 3.0

Ridgeology
The study of the uniqueness of friction ridge skin and its use for 
personal identification (individualization).
SWGFAST, Glossary - Consolidated 09-09-03 ver. 1.0
http://www.swgfast.org/Glossary_Consolidated_ver_1.pdf

Ridgeology is a term developed in 1982 by Sgt. David Ashbaugh to describe 
the scientific evaluation process used for friction ridge identifications.

Roquerre, Donald Daring
In 1934, in an attempt to conceal his identity, Donald Daring Roquerre mutilated 
his fingerprints by conducting surgery on himself.  He removed sections of skin 
and exchanged them with other areas.  In some fingers he merely changed the 
direction of the skin.  In 1953 he was arrested, the alteration of his fingerprints 
was discovered and he was still easily identified.

Rosaniline Chloride
See Basic Fuschin.
SWGFAST, Glossary - Consolidated 09-09-03 ver. 1.0
http://www.swgfast.org/Glossary_Consolidated_ver_1.pdf

Rose Bengal
A fluorescent dye stain used with an alternate light source to visualize cyanoacrylate 
ester fumed friction ridge detail.  The results using this method were minimal and 
its use diminished in the 1980’s.

Ross, Marion
Marion Ross was the murder victim in a 1997 SCRO murder case involving 
erroneous identifications.

See. McKie Case.

Rubber Lifter
A sheet of flexible rubber with a small amount of adhesive on one side used to 
lift latent prints for preservation.  The advantage of using a rubber lifter 
is that because of it's flexibility, latents can be lifted off of textured and 
curved surfaces.  Rubber lifters are also helpful in lifting latent prints off 
of paper items because they won't rip the paper.  Latents lifted with rubber 
lifters will have reversed images.

Rubbing Technique
Powdering technique that can develop friction ridge detail when 
substrates are rubbed with gloves or cotton dipped in powder, usually 
after surfaces are cyanoacrylate fumed.
SWGFAST, Glossary - Consolidated 09-09-03 ver. 1.0
http://www.swgfast.org/Glossary_Consolidated_ver_1.pdf

Rudimentary
1. Of or relating to basic facts or principles; elementary.
2. Being in the earliest stages of development; incipient.
3. Biology. Imperfectly or incompletely developed; embryonic: a rudimentary beak.
The American Heritage ® Dictionary of the English Language, Fourth Edition
Copyright © 2000 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. 
http://dictionary.reference.com/search?q=rudimentary 05-13-03

Rudimentary Ridge
Due to the definitions of Rudimentary, a rudimentary ridge could refer to either 
the primary and secondary ridges or refer to incipient ridges. It is more common 
to see them referred to as incipient ridges.

Also known as an incipient ridge, a nascent ridge or a subsidiary ridge.

Ruga (plural: rugae)
A fold or wrinkle.  In friction ridge identification the rugae refers to friction 
ridges.

Ruhemann's Purple
Colored compound that is the product of the reaction between amino 
acids and ninhydrin.
SWGFAST, Glossary - Consolidated 09-09-03 ver. 1.0
http://www.swgfast.org/Glossary_Consolidated_ver_1.pdf

Rule 16 Discovery and Inspection, section (a) (1) (G) Expert Witnesses
(As amended to December 1, 2011)
At the defendant's request, the government must give to the defendant a written summary 
of any testimony that the government intends to use under Rules 702, 703, or 705 of the 
Federal Rules of Evidence during its case-in-chief at trial. If the government requests 
discovery under subdivision (b)(1)(C)(ii) and the defendant complies, the government must, 
at the defendant's request, give to the defendant a written summary of testimony that the 
government intends to use under Rules 702, 703, or 705 of the Federal Rules of Evidence 
as evidence at trial on the issue of the defendant's mental condition. The summary 
provided under this subparagraph must describe the witness's opinions, the bases and 
reasons for those opinions, and the witness's qualifications.

Rule 701. Opinion Testimony by Lay Witnesses
(As amended to December 1, 2011)
If a witness is not testifying as an expert, testimony in the form of an opinion is 
limited to one that is:
(a) rationally based on the witness’s perception;
(b) helpful to clearly understanding the witness’s testimony or to determining a fact 
in issue; and
(c) not based on scientific, technical, or other specialized knowledge within the scope 
of Rule 702.

Rule 702. Testimony by Expert Witnesses
(As amended to December 1, 2011)
A witness who is qualified as an expert by knowledge, skill, experience, training, or 
education may testify in the form of an opinion or otherwise if:
(a) the expert’s scientific, technical, or other specialized knowledge will help the 
trier of fact to understand the evidence or to determine a fact in issue;
(b) the testimony is based on sufficient facts or data;
(c) the testimony is the product of reliable principles and methods; and
(d) the expert has reliably applied the principles and methods to the facts of the case.

Rule 703. Bases of an Expert’s Opinion Testimony
(As amended to December 1, 2011)
An expert may base an opinion on facts or data in the case that the expert has been made 
aware of or personally observed. If experts in the particular field would reasonably rely 
on those kinds of facts or data in forming an opinion on the subject, they need not be 
admissible for the opinion to be admitted. But if the facts or data would otherwise be 
inadmissible, the proponent of the opinion may disclose them to the jury only if their 
probative value in helping the jury evaluate the opinion substantially outweighs their 
prejudicial effect.

Rule 705. Disclosing the Facts or Data Underlying an Expert’s Opinion
(As amended to December 1, 2011)
Unless the court orders otherwise, an expert may state an opinion — and give the reasons for 
it — without first testifying to the underlying facts or data. But the expert may be required 
to disclose those facts or data on cross-examination.

Rule 1001. Definitions That Apply to This Article
(As amended to December 1, 2011)
In this article:
(a) A “writing” consists of letters, words, numbers, or their equivalent set down in any form.
(b) A “recording” consists of letters, words, numbers, or their equivalent recorded in any manner.
(c) A “photograph” means a photographic image or its equivalent stored in any form.
(d) An “original” of a writing or recording means the writing or recording itself or any 
counterpart intended to have the same effect by the person who executed or issued it. For 
electronically stored information, “original” means any printout — or other output readable 
by sight — if it accurately reflects the information. An “original” of a photograph includes 
the negative or a print from it.
(e) A “duplicate” means a counterpart produced by a mechanical, photographic, chemical, electronic, 
or other equivalent process or technique that accurately reproduces the original.

Rule 1002. Requirement of the Original
(As amended to December 1, 2011)
An original writing, recording, or photograph is required in order to prove its content unless these 
rules or a federal statute provides otherwise.

Rule 1003. Admissibility of Duplicates
(As amended to December 1, 2011)
A duplicate is admissible to the same extent as the original unless a genuine question is raised about 
the original’s authenticity or the circumstances make it unfair to admit the duplicate.

Rule 1004. Admissibility of Other Evidence of Content
(As amended to December 1, 2011)
An original is not required and other evidence of the content of a writing, recording, or photograph 
is admissible if:
(a) all the originals are lost or destroyed, and not by the proponent acting in bad faith;
(b) an original cannot be obtained by any available judicial process;
(c) the party against whom the original would be offered had control of the original; was at that time 
put on notice, by pleadings or otherwise, that the original would be a subject of proof at the trial or 
hearing; and fails to produce it at the trial or hearing; or
(d) the writing, recording, or photograph is not closely related to a controlling issue.

Russell-Turner, William
Inventor of the Comparator.

Ruthenium Tetroxide (RTX)
Reagent used in the visualization of friction ridge detail, 
especially on fabrics.
SWGFAST, Glossary - Consolidated 09-09-03 ver. 1.0
http://www.swgfast.org/Glossary_Consolidated_ver_1.pdf

A chemical used in a fuming method to develop friction ridge detail on porous items.  
RTX reacts with sebaceous material leaving dark gray images.  This process can be used 
on thermal paper, human skin, fabric, leather, glass, plastic, tape, wood, metal, stone, 
walls, and wet surfaces.



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