You have already recovered evidence from the victim’s personal effects – it is now time to see what we can learn from this evidence by testing it in the laboratory. A lab technician from Devon and Cornwall Constabulary will be on hand to advise you, but make sure you have read and understood this task before heading over to the lab.

1. The threatening letter you found has been tested by the police lab technician who has analysed the ink it was written with. Click on the image below to see this analysis:

Your group must try and find out which exact ink was used in the letter – this could help prove who the murderer was. You will be carrying out chromatography tests on a number of different inks and trying to match them to the sample above. Click here for the experiment method which you should take with you to the lab

Each group must;

• use chromatography to identify the ink used in the letter
• use a Lab Report sheet from your case file to record your results
• add anything you find out about the murderer to your Unknown Suspect Log
• email your findings to sgt.knight@csibroadclyst.co.uk with your group number and the word ‘Chromatography’ in the subject line

2. The fibres you discovered on the victim’s jacket need to be identified – they might also be a link to the murderer.

The police technician has used a digital microscope to photograph fibres from the train and the victim’s clothes – can you match the fibres you found to these photos, or do your fibres come from somewhere (or someone) else?

Click here for the sample fibres

Click here for Fibre Analysis instructions which you will also need to take with you

Each group must;

• use the digital microscope to take photographs and identify the fibres you found
• use a Lab Report sheet from your case file to record your results
• add anything you find out about the murderer to your Unknown Suspect Log
• email your findings to sgt.knight@csibroadclyst.co.uk with your group number and the word ‘Fibres’ in the subject line