Beijing Law Review
2013. Vol.4, No.4, 137-140
Published Online December 2013 in SciRes (
Open Access 137
Applications of Forensic Science in Private Security
Danielle Sapse
Department of L aw, Police Science, and Criminal Justice Administration, John Jay College of Crim inal Justi ce,
New York, USA
Email: dsapse@jjay
Received October 1st, 2013; revised Octo be r 29th, 2013; accepted N ovember 26th, 2013
Copyright © 2013 Danielle Sapse. This is an open access article distributed under the Creative Commons Attri-
bution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the
original work is properly cited.
Private security guards are a necessity at the present time, as a complement of the police departments in
order to combat crime and terrorism. Both police forces and private security organizations are greatly
helped in their work by the methods of forensic science. Forensic science applies scientific methods to the
solving of crimes. These methods include fingerprinting, drug analysis, DNA (Deoxyribonucleic Acid)
studies, ballistics, arson and explosive investigations, and studies of glass fragments. Fingerprinting and
urine, saliva, or hair analysis for the presence of drugs are essential for the hiring of private security
guards, in order to establish their suitability for the position.
Keywords: Forensic Science; Security; Fingerprints; DNA
In modern times, issues of security have an increasingly im-
portant impact on the public awareness. Because of the ram-
paging crime present in our society, it is necessary to comple-
ment the police force with private security. Private security can
be provided either by in-house guards or by those from contract
guard agencies, or a combination.
Guard companies are of many different sizes, from some
with less than 100 employees, to those with many thousands.
These security corporations face many difficulties. Many of
these are related to the hiring and training of the guards. There
are times when the number of guards required for a situation is
unpredictable. For example, if there is a strike, blackout, riot, or
other emergency situation, many additional guards might be
needed on very short notice. Some agencies can provide, in
addition to guards, motor vehicles and other types of equip-
Security guards come from many different backgrounds. For
example, some of them are college students; some are retired
police officers. Some of them are people who want to start a
career in the security business, continuing to be promoted to
higher positions, while others only want to work part-time to
supplement another job. In the United States, men and women
of any age over 18 can work as guards, and this includes many
Applicants find out about positions in many different ways.
There are ads in newspapers, referrals from other guards, and
also employment agencies. The turnover of the security force
varies highly ranging from a few months to several decades
(Sapse, 1980).
In order to provide the best possible workforce, scientific
methods are needed for the screening of prospective guards.
The data obtained through the application of these methods
have to be classified, selected, and stored. These processes also
help decide on the appropriate person for a specific position.
Many security guard companies are interested in finding out
if applicants have a criminal record because it might impact
their decision to hire them. To help obtain this information,
each prospective guard has to be fingerprinted. The prints are
checked with the appropriate law enforcement agency. Another
important issue in accepting a candidate as a guard is whether
or not he or she uses illegal drugs. Fingerprinting and drug
testing both pertain to the field of forensic science.
Civil Law
Besides criminal issues, security companies can be involved
in civil cases (non-criminal) related to litigations. Forensic
science methods are also applied to civil matters.
There are a number of characteristics that make civil law
cases different from criminal law cases. Civil law cases deal
with issues such as negligence, property law, contracts, and
family law. In civil lawsuits one party (called, depending on the
country a plaintiff, claimant or pursuer), is suing another,
(called the defendant or defender). The prosecutor is not in-
volved, and the rights related to counsel and juries are different.
Also, the standard of proof to find a defendant liable (the term
for guilt in civil law) is lower. The plaintiff has to prove liabil-
ity only by a preponderance of the evidence (more likely than
not). To prove guilt in a criminal court, the prosecutor must
prove guilt beyond a reasonable doubt (that is, with a very high
certainty) (Sapse, 2007).
Some civil law issues might be related to the security busi-
ness. Part of the security surveillance consists in rounds by car
to different locations. It is possible that a collision takes place
between one of these cars and another vehicle. As in any case
of collision, one of the points of interest is the identification of
glass fragments. As will be shown later, an area of forensic
science deals with this analysis.
An important aspect of the private security business is related
to Forensic Science. Forensic science is the application of sci-
ence to the law. It is an umbrella discipline including, besides
fingerprint analysis and drug testing, many other sub-categories,
such as DNA studies, toxicology, ballistics, trace evidence, and
document examination. All of the above mentioned subjects are
covered by the part of forensic science called criminalistics.
Criminalistics is the identification, examination, and interpreta-
tion of physical evidence. It includes four categories: analysis
of materials evidence, forensic chemistry, biological evidence
analysis, and pattern evidence.
These subjects are studied mainly by chemical and biological
methods. Such issues as chemical reactions, separation of
chemicals of forensic interest by analytical procedures, and
enzymatic reactions are all examined with such techniques as
spectroscopy (Nuclear Magnetic Resonance, Infrared or Mass),
electrophoresis, and other techniques.
Forensic science also includes areas such as forensic anthro-
pology, pathology, entomology, odontology, psychology and
psychiatry(Gaensslen, 2008).
The analysis of physical evidence found at a crime scene can
be crucial to solving crime. In addition, these methods can be
used to assist in the hiring of guards. They can contribute to the
obtaining of information about an individual and discover this
way if that individual might have a past which makes him or
her inappropriate to function as a security guard.
The analysis of evidence and other forensic issues is per-
formed in specialized laboratories all over the world. Because
of its importance to society, the governments of many countries
fund forensic science laboratories. These labs can have budgets
ranging from less than one million dollars a year to many mil-
lions, depending on the size and the number of employees. The
equipment in these laboratories can include microscopes, com-
puters, and other analytical instruments, as well as sophisticated
spectrophotometers, NMR (Nuclear Magnetic Resonance) and
x-ray equipment, lasers, and others (Gaensslen, 2008).
One of the main purposes of forensic labs is to analyze
physical evidence. Physical evidence is evidence pertaining to
objects found at the scene of the crime. Some examples are
toolmarks, fingerprints, footprints, and glass fragments. An-
other type of evidence, other than physical evidence, is testi-
mony, which is spoken evidence (that is, information conveyed
by witnesses). Forensic analysis performed on physical evi-
dence can sometimes contradict testimony that is given in court,
which is not always completely reliable. Witnesses can forget
important facts or even lie, but physical evidence is often more
One of the most precise methods to identify a person is by
their fingerprints. Every person’s fingerprints are different—
even those of identical twins. Also, they do not change
throughout a person’s life, except on very rare occasions (such
as serious skin damage). Fingerprints can be identified by com-
plicated patterns on friction ridge skin called loops, arches, and
whorls. These were first defined in the book Finger Prints by
Sir Francis Galton, in 1892.
In order for fingerprints to be used properly, it is important
for them to be obtained, stored, and analyzed correctly. This
can be done with an Automated Fingerprint Identification Sys-
tem (AFIS). These are systems of computers and software that
can match known and unknown fingerprints. In the United
States, the Integrated Automated Fingerprint Identification
System (IAFIS) is a system maintained by the Federal Bureau
of Investigations and agencies can submit fingerprint informa-
tion to it. The IAFIS contains the fingerprints of more than 55
million people. Fingerprints are sent not only for arrested sus-
pects, but also for employment and other non-criminal purposes
(, 2009).
As mentioned above, candidates for security guard positions
may be fingerprinted in order to determine if they have been
involved in criminal activity. AFISs not only can help discover
information about current crimes, but also older ones, in situa-
tions where new technologies allow for new information to be
discovered. Fingerprints may be used together with other bio-
metric systems, such as iris scans and retinal scans, in order to
obtain more accurate results.
Fingerprints can be detected when chemical substances are
secreted from the pores within the ridges on fingertips. These
chemicals are deposited in a pattern that reflects the pattern on
the friction skin (Sapse, 2007).
One very important chemical method of identifying finger-
prints is the use of a chemical called Ninhydrin. This chemical
reacts with amino acids found in the perspiration in fingerprints
and produces a purple-bluish substance.
Another part of forensic science research, due to the fact that
it permits a very precise identification of individuals, is DNA.
DNA (Deoxyribonucleic Acid) is a chemical found in the nu-
cleus of cells, and plays a fundamental rule in heredity and in
many biological phenomena.
In the security business, DNA analysis, even though not ap-
plied routinely in the hiring of guards, might be applied for
identification of suspects at an eventual scene of a crime. It can
also determine the presence of a guard at a certain scene.
In the United States, the FBI (Federal Bureau of Investiga-
tions) also has a national DNA database called CODIS (Com-
bined DNA Indexing System). DNA databases match DNA
evidence found at a crime scene with known DNA records.
DNA can identify a person with an accuracy of more than
99.9%. Other countries also have national databases, such as
the UK National Criminal Intelligence DNA Database and the
FNAEG in France.
There are many examples of the usefulness of DNA in the
solving of crimes. For instance, in 2012, a security guard was
shot and killed while working at an apartment complex. At first,
it was not clear who committed the crime. Surveillance cameras
showed a man on a bicycle near the scene of the crime, who
was suspected to be the killer. The security guard company for
which the victim worked offered a $10,000 reward for informa-
tion leading to an arrest. A few days later, an arrest was made
of a sixteen-year old who was then charged with the murder, as
well as armed robberies and other crimes. This was a situation
in which DNA could be used to identify the criminal. A bicycle
was left at the scene of the crime and was analyzed for DNA;
the DNA was shown to match the suspected murderer (Ingles,
There was another case in which a security guard was ac-
cused of the murder of many women, apparently mostly prosti-
tutes, over several years. He was charged with murder, sexual
assault, and kidnapping.
DNA was gathered from the bodies of two of the victims,
one that was found in 2002 and the other that was found more
Open Access
recently. The DNA was found to be from the same person. The
second victim’s body was found near a site where security
guards worked. The police showed the surviving victims pic-
tures of guards from the firm, and they identified the suspect.
The guards, including the suspect, voluntarily gave DNA sam-
ples and this way, a match was found with the suspect (Pin-
kerton, 2011).
Another type of important scientific evidence is glass. As
shown before, glass identification, for instance, at a scene of a
car collision can p ro ve important.
Glass has properties that can identify it, such as density
(which can be determined from the mass and volume) and re-
fractive index. The refractive index is a number which de-
scribes the way the light passes through a substance, such as
Discovering the elements in glass is another way to distin-
guish one sample of glass from another. Glass is made from
sand, so the composition of the glass will depend on the com-
position of the sand. Sand from different places will contain
somewhat different substances, and this will create a difference
in the glass. As far as the chemical composition is concerned,
glass contains several different combinations of elements. Some
of the elements present in glass are silicon, calcium, and oxy-
gen, as well as many others in various amounts (Gaensslen,
Weapons and Ballistics
Weapons are a part of many crimes, so it is useful to be able
to recognize which ones were used. The determination of who
fired a weapon can distinguish a criminal from an innocent
To obtain such information, gun residues have to be analyzed.
Residue (made of gunpowder, primer, metals from the bullet,
and dirt) can be found on the suspect's hands, and also on vari-
ous surfaces. The pattern of residue on a surface can help to
show the distance from which the gun was shot. Sometimes the
pattern can be seen easily, but often, it has to be chemically
enhanced to be seen.
Ballistics is the study of the trajectory of the bullet. This way,
the position of the suspect and the victim can be discovered.
Some of this information can come from the entry and exit
wounds on the victim’s body.
Arson and Explosives
A category of crimes particularly subjected to investigation
by security forces together with the fire depa rtment is re lated to
arson and explosives.
Arson is the burning of a structure. Traditionally, it was the
burning of a home belonging to another person, but now, it can
be the burning of any type of structure, including one’s own
house, as long as it is intentional; that is, not an accident. There
are a number of reasons why people commit this crime. It could
be for insurance reasons, to cover up another crime, or simply
to damage property (Scheb, 2007).
The process of burning is called combustion. It is an oxida-
tion reaction that occurs when oxygen combines with carbon to
form carbon dioxide, and the reaction gives off heat(Gaensslen,
When there is a fire, it is important to determine whether it
was caused by arson or was an accident or natural disaster.
There are a number of ways in which the cause of a fire can be
Investigators will try to find out the point of origin, that is,
the location from which the fire started. If there are several
points of origin this may indicate that the fire was set intention-
ally. One way of finding this out is by examining the burn pat-
tern. For instance, if the pattern is a cone shape, the point of the
cone could be the point of origin.
Also, burn patterns can indicate the way that a fire was
started. For example, wildfires often move in a certain type of
pattern and spread outward and move faster uphill. These pat-
terns can also indicate if the fire was started with gasoline or
another type of fuel. Also, certain types of burned trees and
grass can be indicative of a naturall y occurring fire.
There are many incidents of crime that involve explosives:
These crimes can be terrorist acts or crimes targeted at an indi-
vidual, such as a bomb placed under a car. Governments at all
levels: local, state, and federal, have agencies that address
themselves to this type of crime.
Explosions require a small amount of energy to start and a
large amount of heat is produced. It is clear that security guards
should be very vigilant in preventing arson and explosions. The
guards should be attentive to any unusual noises or odors that
could indicate a crime of arson or bombing about to be com-
Security guards who take drugs can be a serious problem.
Guards may have weapons or use vehicles and being under the
influence can affect them and cause grave consequences. Also,
guards sometimes have to make instant decisions and so their
judgment should not be impaired by drugs.
Because of this, many security guard companies perform
drug tests on prospective employees. Some companies test
routinely, while others do so only if the client requests it and
pays for it.
There are different drugs that can be tested for, including
cocaine, marijuana, opiates, methamphetamines, amphetamines,
phencyclidine (PCP), benzodiazepines, barbiturates, methadone,
tricyclic antidepressants, and others. There are several ways to
test a person for drugs. Three of the most common are the test-
ing of urine, saliva, or hair. Each one has advantages and dis-
advantages. Urine tests give instant results and can test for
many different types of drugs; however there is a possibility of
tampering. Saliva testing has the advantage of being convenient
and not invasive, and it can detect recent drug use. The disad-
vantages are that the results depend on the individual rate of
saliva production and the nature of the drug used. Also, it can
only detect the recent use of drugs. Testing of hair is the most
effective and convenient method, however it requires a longer
waiting period and can be more costly. Also, it may not detect
very recent use of drugs (
Since the security business is strongly involved in preventing
crimes and if crimes do occur, in participating in their solving,
knowledge about the forensic science methods is a valuable
asset for the security workforce.
Open Access 139
Open Access
Drug testing network, inc.
Gaensslen, R. E., Harris, H. A., & Lee, H. (2008). Introduction to fo-
rensic science and criminalistics. New York, NY: McGraw-Hill
Companies, Inc.
IAFIS (2009). All about integrated automated fingerprint identification
Ingles, J. (2012). 16-year-old boy arrested for security officer murder,
ATM armed robberies. ABC Action News.
Pinkerton, J. (2011). Guard may be linked to killings of 15 prostitutes.
Sapse, A. M., Schenkin, P., & Sapse, M. (1980). Computer applications
in the private security business. New York, NY: Praeger.
Sapse, D. (2007). Legal aspects of forensics. New York, NY: Chelsea
Scheb, J. M. & Scheb, J.M. II. (2012). Criminal law (6th ed.). Belmont,
CA: Wadsworth.