The forensics lab was in a modern office block close to Manchester University. Hannah greeted them both at the door and ushered them through to the secure facility.
The green striped backpack Ridpath had last seen at the children’s home was sitting on a lightbox table in the middle of the room. Around it, technicians worked, staring through microscopes, adjusting sampling slides, standing over centrifuges spinning loudly.
‘Right, we’ve had a look at the backpack and we’ve come up with a few points of interest. Firstly, the pack itself is pretty distinctive – luckily it’s not one of your common or garden ones like Jansport, used by millions of kids.’
‘I’ve never seen one like it,’ said Ridpath.
‘It’s because only six hundred were produced. As the large logo says, it was manufactured as a limited edition by CLAK in 2009. The factory is in Leicester and they are still operating today.’ She passed the contact details to Ridpath. ‘I’ll leave it to your team to follow up.’
‘Team?’ sneered Dave Connor. ‘You’re looking at it.’ He pointed at Ridpath and himself.
‘Shall I continue?’
‘Please, Hannah, give us some good news.’
‘Good news coming up. There was nothing in the main pocket of the bag, but in one of the side pockets, hidden behind the plastic lining, we found this.’ From beneath the table, she produced a picture of a small stub with a frayed end stained brown. The scale next to the object showed it was just less than one centimetre in length.
‘What is it?’ asked Dave Connor.
‘It’s the end of a joint. A roach.’
The crime scene manager smiled. ‘Right first time, Ridpath. It’s a rolled-up piece of paper, I’d say 110gsm. We tested it for DNA and then we opened it up.’ She produced another picture, again with a scale. It was a piece of orange paper four centimetres long and less than one centimetre wide. ‘It seems to have been torn from a flyer of some sort.’
Ridpath could make out the beginnings of printed words at the side, but they were very faded. ‘It looks like an M, then an F, the rest is too faded to see. There seems to be drawing of some kind at the bottom.’
‘We have one of our forensic document investigators on it at the moment to see if we can find the source material. I’ll get back to you as soon as I can.’
‘How are you going to be able to see anything?’ asked Dave Connor.
‘We’ll use the VSC.’
‘What’s one of those when it’s at home?’
‘Using different wavelengths of light, a video spectral comparator can reveal writing or printing which has faded over time. We process and enhance the result to appear far darker and, hopefully, more legible.’
‘When will you know?’
‘As soon as Mike has finished the work.’
‘But when?’
‘When he’s finished,’ Hannah emphasised.
‘Did you find anything else?’ interrupted Ridpath before the crime scene manager totally lost the plot with Dave Connor.
‘Nothing, it was clean as a whistle.’
‘Any fingerprints on the backpack?’
‘None. Whoever placed it in the larder was wearing gloves, or was careful enough not to leave any trace of themselves.’
Ridpath thought of a question. ‘Any DNA on the roach?’
‘Great minds think alike, Ridpath. We’re trying to process it, but we’re not hopeful of a result.’
‘Why?’ asked Dave Connor.
Hannah sighed loudly, as if she had explained this a thousand times to a thousand different detectives. ‘There are four steps in DNA processing: extraction, quantitation, amplification and capillary electrophoresis. We’ve done this first, which is extraction. The lab technicians are now seeing if the DNA has been contaminated and if enough can be extracted to provide a viable result.’
‘Contaminated?’
‘It’s sat in the bottom of backpack on the end of a roach for countless years; mould, damp, heat or any of a hundred other environmental factors may have degraded the DNA.’
‘Right.’ Dave Connor scratched his head. ‘When will we know?’
‘A couple of days.’
‘What about the DNA and the fingerprints from the hands?’
‘A different set of problems. They were immersed in an embalming liquid with the following chemical composition.’ She checked her notes. ‘Twenty-two per cent formaldehyde, forty-three per cent methanol and eight per cent glutaraldehyde. The rest is water and fragrant oils.’
‘And this helps us how?’ asked Dave Connor.
‘Different manufacturers use differing quantities of chemicals in their embalming liquids. We should be able to find out who made the stuff our hands were swimming in.’
Dave Connor frowned. ‘Right, all gobbledygook to me.’
Hannah continued. ‘And because they were immersed in an embalming liquid, we’re having to use a special technique to extract the DNA.’
‘Special technique?’
‘Formaldehyde causes DNA damage, chemical modifications and degradation, thereby reducing the quantity and quality of DNA available for downstream genetic analyses. However, DNA can be obtained from embalmed nail samples using the QIAamp FFPE, quantified using the QuantiFilerTrio and genotyped using the GlobalFiler®PCR Amplification. Do you really want me to spend the next hour explaining to you the details of these processes?’
‘No, thanks.’ Both Ridpath and Connor spoke at the same time.
‘Suffice to say, we may be able to get DNA from the nails even though they were embalmed.’
‘Great, when can we have the results?’ asked Dave Connor.
‘It takes time. We also have the nail scrapings from the post-mortem to handle, plus the fingerprints from the hands. Do you know how difficult it is to identify people when all you have are the hands?’
‘I know, but we’re up against the clock too.’
‘A couple of days, maybe earlier, I should have something.’
‘You’re a star, Hannah.’
‘But I’m not promising, Ridpath, so don’t try to butter me up.’
‘No, but you’re the best, Hannah. I’m sure you’ll get us the results as soon as you can.’
‘You’re such a bullshitter, Ridpath, but I’ll do my best. Now, if you have no other questions, get out of here and let me do my job.’