Creat ive Educati on
2011. Vol. 2, No. 1, 18 -21
Copyright © 2011 SciRes. DOI:10.4236/c e.2011.21003
Large Scale Simulation for Education in Forensic DNA Science
Jason M . Ki n ser
Department of Bioinformatics and Computational Biology, George Mas on U niversi ty, Fairfax, USA
Received January 12th, 2011; revised February 24th, 2011; accept ed February 28th, 2011.
Forensi c scienc e education is a ra pidly expandi ng field with se veral univers ities a dding degrees i n many
forens ic scienc e discipl ines. Concurrently, with this expansion is a new push for forensic science educa-
tion i n the secondar y schools. This genera tion of st udents is al so very a dept at comp uter genera ted envi-
ronments. The logical progression is therefore to provide students and instructors with a simulated envi-
ronment t o i mmerse st udent s int o forens ic s cienc e invest igat ions. The Island of Ti r Eb ensëa is a de velop-
ing system that generates a large scale population and forensic scenarios and places the students as the
investigators. Students are provided with a scenario and then generate queries to gain information about
the people involved in the case. They can then draw conclusions about the scenario and compare these
conclusions to the know n answer. The simulat ion is availab le to educat ional ins titutions.
Keywords: Web-Based Education, Forensic Science, DNA
Forensic science has become a very popular field in educa-
tion within the last few years. One popular explanation is the
advent of television shows such as CSI. Another contributing
factor though is the recent development in the science itself.
Modern forensic science technology has evolved rapidly in the
past decade. Furthermore, the employment future in the field is
bright with a predicted increase of 20% in jobs before 2018
(Bureau of Labor Statistics, 2011;, 2011;
Jaroch; 2011). Colleges and universities have responded to this
need as noted by a recent survey which indicates that the US
now has over 70 degree programs in this field (Tebbett, Wielbo,
& Khey, 2007). Likewise, opportunities for secondary school
stud ent s are in creasi ng i n t he t erms of summer ca mps, s peci alt y
programs and school clubs.
This new generation of students is also very adept in using
computerized social environments with the onset of social net-
works and simulation games. Many studies have indicated that
learning experience for secondary school students is enhanced
through the use of virtual environments and simulations (Akpan
& Andre, 2000; Choi & Gennaro, 1987; Geban, Askar & Ozkan,
1992; Lewis, Stern & Linn) with some studies measuring im-
proved performances (Huppert, Lomask & Lazarowitz, 2002;
Mintz 1993; Willing 1988).
In the study of forensic DNA science it is necessary for stu-
dents to understand the statistics of large populations as well as
the inheritance properties of DNA profiles. This type of analy-
sis is well suited for a large scale simulation which is the foun-
dation of a project named Tir Ebensëa. The simulation provides
students with forensic scenarios and several portals through
which their inquiries can reveal more information about the
case. Students then use spreadsheets to reach conclusions of the
scenarios which can be compared to the known answers. The
simulation is available to educational institutions by request to
the au thor.
Simulation Requirements
The study of human identification through DNA profiles re-
quires several components. The two major components are the
statistical analysis of large populations and the understanding of
the DNA profiles including their inheritance properties. Fu r-
thermore, realism in an investigation must includ e several ot her
complicated facto rs. The simulation incorporates many of these
properties to provide realistic scenarios for the students.
DNA Profiles
Currently, a human DNA profile used in court cases may
consist of three components. The first is STR (short tandem
repeats). In the nuclear DNA there are many loci in which a
small DNA pattern repeats multiple times. A forensic profile
identifies alleles by the number of repeats. The nuclear profile
includes contributions from both biological parents and thus for
each locus there are two values. As an example, a person’s
profile for a single locus could be the allele pair [9,11] which
ind icates along on e strand of th e DNA helix th ere are 9 repeats
and along the other is 11 repeats. However, it is not known
which parent donated which value. There is no worldwide
standard yet on the set of loci used. The FBI database, named
CODIS, uses 13 loci. European countries with their smaller
populations often use a fewer number of loci of which some
differ from the US set.
Consider a case of a single locus. The parents are [7,9] and
[9,10]. A child produced from these two parents will receive
one value from each. Therefore a child could be: [7,9], [7,10],
[9,9] or [9,10] with equal probabilities. It is quite possible to
reconstruct (at least partially) a person’s STR profile from the
profiles of their immediate relatives. Given a case where the
mother is [7,8] and two children are [7,10] and [8,11], it is
possible (excluding mutations) to reconstruct the father’s pro-
file to be [10,11]. Even though the father’s DNA may not be
available it is possible to reconstruct (at least in part) the fa-
ther’s profile.
The second type of DNA profile use is mitochondrial DNA
which is a single stranded DNA loop that exists in multiple
copies in the cytoplasm of a cell. The mitochondrial DNA is
inherited en masse from the mother. Statistically, it is treated as
a single entity rather than a set of values such as in the STR
case. The third type of DNA profile is YSTR which is a set of
repeats b ased on th e Y-chromosome. The Y chromosome exists
only in males and is inherited en masse from the father to the
sons. Statistically, it is treated in a manner similar to the mito-
chondrial DNA.
One of the requirements of the simulation is that each person
has a DNA profile with STR, YSTR (males), and mitochondrial
DNA. Furthermore, it necessary that people inherit their pro-
files from their biological parents. There is also a small possi-
bility of some mutations that must be included.
In real life the distribution of allele sizes (Butler 2005; Mar-
janovic et al., 2005; Dutta et al., 2002; Nei 1973) varies for
each ethnic group. It is possible to provide a probability of a
person’s ethnicity based upon their DNA profile. Therefore, th e
simulation must have a variety of ethnic groups each with their
own distributions.
Matching DNA profiles does not prove that a DNA sample
comes from a specific person. There are two conclusions that
can be drawn from an analysis. The first is an exclusion where
it is possible to state that a DNA sample does not come from a
specific person. The second is a probability in which the re-
searcher provides a probability of a random person having a
particular profile. In some cases, this value can be so ridicu-
lously low that it would take several times the Earth’s popula-
tion before there is a significant chance of a second person
having the same profile. While it is not possible to conclude
that a DNA sample comes from a specific person it is possible
to compute that the probability of two people having the same
profile is astronomical.
Before a student can make a statistical calculation from a
sample population it is necessary to gather a subsample popula-
tion. Even though the US population is over 300,000,000
people studies indicate that less than two hundred people are
need to provide a statistically relevant sampling of the popula-
tion (Chakraborty, 1992). In order to replicate this, the si mula-
tion is required to have a large population but not nearly on the
same scale as t he US pop ulation.
In order to replicate this type of analysis it is necessary for
the simulation to have a population base with different ethnic
groups with signature distributions. Furthermore, it is necessary
that t he size of the population be large.
Bi ological versus Le gal Parentage
The DNA profiles are inherited from biological parents.
However, many children live with adults that are legally their
parents but not biologically their parents. This occurs through
re-marriages, adoptions, or infidelities. In some cases, the in-
vestigator may know that the parents are not biologically re-
lated and in other cases this information is not volunteered by
the family members.
Therefore, the simulation must include mechanisms by which
families may be created through means other than biological
evolution. It must include marriages, divorces, re-marriages,
adoptions, and the occasional tryst.
Another major component of a simulation is the creation of
scenarios that are to be solved. In this manner, the students act
as the in vestigators. Scen arios solved by DNA anal ysis inclu de
missing persons, assaults, thefts, scams, law suits, and mass
disaster s. Each scenario presents stu dents with a s mall descrip-
tion and then they interact with the simulation to retrieve other
information that is necessary. A sample case is presented in a
subsequent section.
Require me nts
A simulation of forensic DNA cases must include a large
population with ethnic variations. This population must have
biological relationships in order to replicate inheritance, but it
also must h ave mechanis ms by which these biological rel ation-
ships are disconnected. The simulation must also create scena-
rios suitable for students educational and maturit y levels.
The Tir Ebensëa Simulation
With the requirements in hand the simulation named The
Island of Tir Ebensëa has been created and is available to edu-
cational institutions. The simulation provides a large scale pop-
ulation, portals for inquiry, and forensic scenarios with solu-
The Island of Ti r Eben sëa
The simulation is based upon a theoretical island inhabited
by four ethnic groups. The population occupies five cities as
well as the coun try-side. Since DNA profile statistics are shown
to be sensitive to regions and ethnic groups, four of the five
cities contain a majority of one of the ethnic groups. This al-
lows students to study profile distributions for global, local,
ethnic and/or chronological populations.
The population is evolving at a rate of 10 years per school
semester. Simulants (people in the simulation) age, die, marry,
give birth , etc. du rin g th e cour se of a semester. A recen t sa mple
from the i sland from year 16 27 indicates t hat there have been a
total of 118,000 people of which 24,122 are currently living.
There are four ethnic groups which do marry across racial
boun daries at small rates and there are curr ently 1759 d ifferent
surnames. Figu re 1 shows the distribution of ages of the current
living population. There are two spikes for the younger ages
due to two recent immigration influxes.
The Si mulant s
Each simulant in the population contains a personality which
includes the propensity to commit speci fic criminal act s. Figure
2 displays the distribution of one of the personality factors
which controls the willingness of an individual to cooperate
with the police. Two spikes at the end of the distribution indi-
cate that there are several p eople that will always or never co o-
perate. There is a nontrivial portion of the population that may
cooperate. Students requesting a DNA sample from an individ-
Figure 1.
Dist r ibution of th e ages of the living population.
ual may be denied this information because the simulant does
not cooperate, but the students will not know if this is a tempo-
rary blockade, and requests on different days may produce a
different result.
Figur e 2 depicts on a log y scale the propensity for individuals
in the population to commit a specific criminal act (crime type
1). In this sample, more than 10,000 people have absolutely no
tendency to commit this act. A few hundred people (to the right
of x = 90) are quite capable of committing this act. Several other
personality and criminal propensities are used to describe the
personality of each simulant and some of these qualities are
partially inh erited. Fi gure 3 display s the distribution amongst the
pop u l at i on of a sp e ci fic cri mi n a l te nden cy wher e a la r ger x value
indicates a higher pr o pensi ty to commit this type of cr ime. Cases
are developed bas ed on a person’s criminal tendency profile thus
creating individuals that are recidivists.
Student Interface
Students are required to have two computer tools in order to
participate. The first is access to a web browser to interface
with the simulation and the second is a spreadsheet. The web
sites provide portals in which the students can submit queries.
The results are returned as grids which they copy into their
spreadsheets. Example sheets are available to demonstrate the
methods in which a spreadsheet can be used to complete the
computation. Currently, the material that the student turns in to
the instructor is a small report and the spreadsheet.
Initially, students request a population sampling which they
use to create their base profile distributions. A tool is provided
to create these tables from raw data. Students store this infor-
mation in a spread sheet which wil l be used in almost all scena-
rios. This process is performed just once. When students re-
ceive a scenario they create a new spreadsheet file and store
results from their queries. They also create a copy of th e sheets
from the population sample and add a few cells to compute the
While these steps could be automated, the spreadsheet me-
thod provides a better teaching too l. Stu dents can s ee the stat is-
tics and how they are created and combined to provide a solu-
tion. S tudents need to have a basic knowledge o f statistics ( av-
erages and standard deviations) as well as an introduction to a
Figure 2.
Distribution of cooperation factors.
Figure 3.
Distri butio n or propensi ties to comm it crim e ty pe 1.
few tools used in the forensic industry (Hardy-Weinberg and
upper bounds). These formulae are well within the educational
level of scien ce-minded middle school students.
Students formulate their conclusions which may include ex-
clusions or probabilities. Then the actual solution to the scena-
rio is made available through their instructor. One of the ad-
vantages of using simulation data over real world cases is that
the solution is definitely known.
Finally, tracking software has been installed to follow the
line of inquiry by each student. Information that is easily ob-
tained from this includes the number of queries and the simu-
lants that are being investigated by the students. A simple ar-
gument is that students that achieve results with a minimal
number of queries have performed a better investigation than
students that generate unnecessary queries. However, there are
complicating factors that come with an evolving population.
For example, queries performed on different days may provide
different results since some of the simulants may have died or
been p laced in the j ail. So, the number of inquiries is deemed to
be important but not the only metric.
Sample Case
This section presents a case recently used that indicates the
type of logic that students will need in order to solve a scenario .
In this case, the victim was a discovered body in the forest.
Evidence provided to the students was that the victim was an
adult male, the ethnic group was identified, and the DNA pro-
file of the victim was identified.
The following steps were the ones necessary for the proper
1) Request a list of missing persons from the Missing Per-
sons Bureau. Exclude from consideration all those that were not
adul t males.
2) Prioritize the remaining persons according to location and
3) For each person on the list, contact their immediate fami-
lies and request DNA samples.
4) Exclude from the candidate list those whose DNA profiles
had several mismatches with the victim.
In th is case, only one male (Stanton Updegraff) survived the
previous pruning steps. The following steps were used to con-
firm the identity of the victim.
5) Determine that there were inconsistencies with the DNA
of the wife (Kesha) and three children. From this analysis the
students conclude that Kesha is not the biological mother of the
6) Through queries to other agencies students gather birth
records and marriage records. From this they learn that Stanton
was previously married to Serena and that the birth of the three
children was during this first marriage.
7) Use Seren a and the thr ee children to reconstru ct Stanton’s
DNA profile. In the initial analysis there are some inconsisten-
cies in the reconstruction and the reconstructed profile does not
match the victim. The early conclusion is that the victim is not
Stanton. However,…
8) Th e inconsistenci es trigger students to realize that one (or
more) of the children has a different biological father. Using
Y-chromosome information students conclude that the two sons
have the sa me bio logical father and that th e Y data matches the
victim. Therefore, they consider a reconstruction without the
9) The new reconstruction shows no mismatches between
Stanton and the victim.
10) Students then use statistical tools to compute the proba-
bility that a random person could have Stanton’s reconstructed
profile. This leads them to conclude that there is an extremely
high probability that the victim is Stanton. This is the correct
This case requires the students to use several tools. Students
will need to be able to reconstruct DNA profiles from relatives,
use Hardy-Weinberg statistics to compute probabilities, and
most importantly to understand the evidence. Twice in this case
students would have to understand that the evidence indicates
that oth er peop le are invo lved in the case ( first wi fe and ano th er
male partner). These latter two conclusions are not derived
from computer tools but solely from the student’s ability to
understand the evidence before t hem.
Final Comments
The current version of the simulation is Tir3 with two new
versions in the pipeline that will add other types of forensic
evidence (other than DNA) and new environments. Instructors
may access the simulation through a request through to the
author. Access is currently controlled but not highly restrictive.
Instructors wishing to participate in this project should contact
the author. Sample cases of the simulation are found on the
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