The DNA detective game Teach article

With the help of a detective game, Kenneth Wallace-Müller from the Gene Jury team introduces the use of DNA in forensics and the ethical questions involved.

Peter has been found dead in his hotel room. Who could have killed him? What DNA evidence can you find at the crime scene and how can you analyse it? Can you find the murderer?

The game is most suitable for students aged 10-15 [note that the reviewer suggested using the activity with older students]. You will need time to print, cut and laminate the resources, 30 minutes to play the game, and additional time for discussion.

Before introducing the game, explain how DNA fingerprinting works. Do not forget to point out the differences between DNA fingerprinting (profiling) and sequencing the complete genome. You may find Hodge & Wegener (2006) and the resources on the Gene Jury website^w1 helpful.

Materials

To run the game, you will need the following materials, all of which can be downloaded from the Gene Jury^w1 website.

• Worksheets (one per student or group)

• One set of DNA evidence cards to be laid out around the crime scene; see Figure 1, left.

• One set of suspects’ statements (green) and the pathologist’s report (purple); see Figure 2.

• Several sets (one per group) of suspect (blue) and victim (purple) DNA profile cards; see Figure 3.
• Several sets (one per group) of cards showing the DNA profiles found around the crime scene and of the people in the DNA database; see Figure 4. Do not give these materials to the students until later.

Ideally, all the materials except the worksheets should be printed in colour and laminated.

Preparing the game

Six students take the roles of the suspects: Alex, Eric, Lisa, Olivia, Melinda and Dave. Give each of the students the statement card and DNA profile card for their character.

One student is the police pathologist; give him or her the pathologist’s report card and the DNA profile card of the victim.

Optionally, one student represents the victim: lying on the floor with a knife (or substitute) nearby. Even if you choose to imagine the victim and weapon, place the five DNA evidence cards (the knife blade, the knife handle, the victim’s fingernails, the victim’s jacket, and the blood on the window) around the ‘crime scene’.

The rest of the class are the investigators, working in groups of about four. Give these students the worksheets.

The teacher plays the role of the chief inspector and the forensics laboratory. He or she needs the sheets with the DNA profiles from the evidence and the DNA database.

Playing the game

The flow diagram (Figure 5, below) illustrates the game sequence.

1. Chief inspector (teacher): read out the introduction to the class.

Last night in the local hotel, a terrible crime was discovered. Peter, a well-known businessman, was found dead in his hotel room by two guests, Alex and Olivia, at 11pm. They immediately telephoned the police, who arrived soon afterwards. The pathologist examined the body, and estimated the time of death at 9pm, not long after Peter had finished dinner.

Peter had held a dinner party that evening with some friends to celebrate finishing writing, by hand, a book about his life. The party had taken place in the hotel dining room with his five friends, who had all stayed that night in the hotel. After the police arrived, the five guests and the hotel maid were woken, and assembled downstairs to be questioned.

2. Investigators: look around the crime scene and use Table 1 to record any evidence (the DNA evidence cards in Figure 1; one example has already been entered in the table below).
   

   Table 1: Collecting the evidence at the crime scene

   Type of sample (e.g. blood or skin)	Where was it found?
   Skin	On the victim’s jacket

3. Investigators: take your evidence to the forensics laboratory (the teacher) for analysis.
4. Police pathologist: read out the report on your analysis of the victim’s body.
   Investigators: make notes about the pathologist’s report.
5. Suspects: read out your statement of who you are and what you know about the crime (Figure 2).
   Investigators: using Table 2, below, make notes on the suspects’ statements. Who do you think could be the murderer? All of them have given you their permission to sample their DNA but the police chief inspector has allowed you to take samples from only three of the suspects. Decide which three to sample.

6. Investigators: take a sample from each of your three chosen suspects (the samples have already been analysed by the laboratory, to make things easy for you).
   Suspects: give your DNA profile card (Figure 3) to the investigators who ask for it.
7. Forensics laboratory: give the investigators the results of the DNA analysis from the crime scene (the victim’s DNA profile), and the DNA profiles found on the evidence (Figure 4).
   Investigators: does the DNA profile of any of your three suspects match the DNA profiles on any of the evidence found at the crime scene?
8. Investigators: using Table 3, below, what can you conclude from your comparison? Do you know who the murderer is? Remember what the suspects said in their statements, and do not forget that not all the DNA found at the crime scene necessarily has anything to do with the murder.

9. Chief inspector: did any of the groups identify the murderer? If not, announce that the investigators can compare the samples taken from the crime scene against a national DNA database. You may choose to let the investigators compare their samples against the database, even if they have identified a murder suspect.
   Investigators: can you find a match between the evidence collected at the crime scene and the profiles in the DNA database (Figure 4)? Who do you think is the murderer?
10. Chief inspector: once all the groups have decided who they think the murderer is, reveal the murderer’s identity as Eric and read out his confession.

After his arrest, Eric decided to confess to the police what happened that night.

In his former life, Eric had been arrested several times for carrying and taking drugs. He had decided to forget his old life, and he now owned his own restaurant. Only a handful of people knew about his past, including Peter. Peter also had a dark past, and had known Eric very well. He decided to write about Eric and include details of his criminal activities in the book of his life story.

On the evening of the murder, Peter was celebrating the completion of his book by having dinner in the hotel with some friends, including Eric. During the conversation over the meal, Eric realised what Peter had written about him in his book, and how it could damage his reputation.

After dinner, all the guests stayed in the restaurant for coffee. Eric finished and went for a walk in the gardens to plan a way to silence Peter and steal his book. He crept into the kitchen and stole a knife, concealing it in his trouser pocket. Eric hatched a plan to meet Peter in his hotel bedroom for a chat, and – when Peter was least expecting it – to kill him using the knife.

Everything went according to his plan, but while Peter lay dying on the floor covered in blood, Eric heard footsteps walking past the room, and as he grabbed the book, he panicked, accidentally dropping the knife.

After quickly walking back to his room, he hid the book in his suitcase in order to destroy it later. He planned to use the excuse of an early business meeting to leave first thing the next morning.

Acknowledgements

This game was developed as a collaborative effort by the Gene Jury team – Heather McQueen, Fiona Stewart, Sarah Keer-Keer and Kenneth Wallace-Müller – at the University of Edinburgh, UK. For more details, see the Gene Jury website^w1.

Thanks to Sandra Couperwhite, forensic scientist with Lothian and Borders Police, for her help with the box ‘How well does the game reflect reality?’

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