‘I have no idea,’ said Marina.
‘Well, you’d better have one just to be sure. I brought some with me.’
He stuck a pre-loaded hypodermic needle into Marina’s bottom as she bent over a lab bench.
‘What do you do here?’ he asked. ‘Reminds me of medical school.’
‘This is a haematology lab,’ she said. ‘We look at blood to try and find a marker for various types of cancer. We take blood cells and cut the proteins into amino-acid chains using the enzyme trypsin. Trypsin is, of course, a protein itself.’
Of course, I thought.
‘We look at the chains of amino acids which make up the proteins and see if there are markers which are certain cancer specific. We pass the chains through this mass spectrometer,’ she pointed at a long grey cabinet that reminded me of a deep freeze. ‘It determines the relative masses of each chain and if there is a variation we are not expecting this may be the marker we are looking for.’
I was completely lost but Geoffrey seemed to understand and he was nodding furiously as he moved around, inspecting the mass spectrometer from every angle.
‘Glad to see my taxes are going to a good home,’ he said.
‘No, no!’ said Marina. ‘This institution and all the research we do here is funded by charitable contributions from the public to Cancer Research UK. We are not supported by taxation. It’s very important to us that people know that.’
‘Sorry,’ said Geoffrey. ‘I stand corrected.’
Marina nodded and took the plastic bag out of the fridge.
‘Now from this little lot,’ she said, getting back to her ‘in lab’ mode, ‘what I want is a DNA profile. DNA is the code for making cells. Proteins are the bricks from which the cells are built. The DNA strands are the architect’s plans that show how the bricks go together to build the cell structures.’
‘So people with different DNA have different cell structures?’ I asked.
‘Absolutely,’ she said. ‘Different DNA produce different-looking people due to slight differences in their architect’s plans. Nearly all the DNA in each person is the same so we all have the same sort of cells — muscles, nerves, skin and so on. We all have two eyes and one nose. It’s just the teeny-weeny differences in the codes which produce our different characteristics, like blue or brown eyes; blondes, brunettes or redheads; black or white skin; short, tall, everything. It’s these minute differences that are distinctive to an individual and it is these differences that allow us to produce a DNA profile which is like a fingerprint, unique.’
Marina was on a roll. ‘I can use restriction enzymes like EcoR1 to cut the DNA strands in this sample into what we call polynucleotides. Then I’ll put them in an agarose gel matrix, a sort of jelly, for electrophoresis. The polynucleotides are charged so they’ll migrate, or move, in the electric field. The amount they migrate is dependent on the size and shape of each polynucleotide. Imagine that the gel acts as a sort of sieve, the bigger the polynucleotide the less distance it will migrate.’
Geoffrey was still nodding. I wasn’t.
‘So in the gel matrix you get separation of polynucleotides into different bands. Then you bake the matrix on to a sheet of nitrocellulose paper to give a permanent pattern of lines where the bands are.’
‘How does that help?’ I was out of my depth here, I thought. Give me a poor jumping novice chaser over Aintree fences any day.
‘Everyone has slightly different DNA so everyone has a different pattern. In criminal cases, they say that the odds of two different people having the same pattern is more than 60 million to one. Unless, of course, you have identical twins. They will have matching patterns because their DNA is exactly the same, that’s what makes them identical. However, what I’m doing wouldn’t be acceptable as evidence in court. The law requires much stricter systems for producing the profile to prevent cross-contamination. This one will be contaminated with my DNA for a start. I’ll have to do another pattern of just my DNA so I can subtract my lines to leave those of our friend alone.’
‘Our friend?’ asked Geoffrey.
‘The door,’ I said.
‘Door? What door?’ Poor Geoffrey was getting very confused.
‘The door Marina walked into, twice.’
‘Ah,’ the penny dropped. ‘Yes, the door, our friend. Good. Well done.’
I wasn’t sure if he understood or not but he seemed happy to wander around the lab as Marina worked away with the fingernails. She then scraped some cells from the inside of her cheek to do another profile of her own DNA alone.
‘It will take several hours now for the polynucleotides to migrate in the gel matrix. We’ll have the results next week.’
‘What will they give us?’ I asked.
‘Nothing on their own,’ she said, ‘but if we get more samples and one of them matches, then, bingo, we have our man.’
‘So all I have to do is go around asking everyone for a DNA sample.’
‘You don’t have to ask,’ said Marina. ‘Just pluck out an unsuspecting hair. As long as the root follicle is still attached, there will be enough cells present to get a profile.’
‘Is that legal?’ I asked.
‘No. Strictly speaking it’s not,’ she said. ‘The Human Tissue Act makes it illegal to hold a sample for the purpose of producing a DNA profile without the consent of the donor.’ She waved her hand at her work. ‘All this has technically been illegal but I’m not telling.’
‘Me neither,’ said Geoffrey flamboyantly. ‘Doctor/patient confidentiality, don’t you know.’
Marina and I went back to Ebury Street while Geoffrey returned home to Highgate.
‘See you next week to take the stitches out,’ he had said as he got into his Volvo. ‘Take care with that girl of yours. I’ll send you my bill.’
He hadn’t sent me a bill for years.
We arrived back home at about ten thirty, far too late to go out to eat, as I had planned.
‘Package for you, Mr Halley,’ said the night porter as we arrived. Derek had gone off duty.
The package was, in fact, a brown manila envelope about seven by ten inches. It had ‘SID HALLEY — BY HAND’ written in capital letters on the front.
‘When did this arrive?’ I asked the porter.
‘About five minutes ago,’ he said. ‘It came by taxi. The driver said he had been paid to deliver the package and that you were expecting it.’
‘Well, I wasn’t.’
I opened the flat envelope. There was a single sheet of paper inside. It was a newspaper cutting from Monday’s Pump. It was the picture of Marina and me walking down the road, hand in hand. This copy had some additions.
‘Listen to the message. Someone could get badly hurt’ was written across the bottom of the picture in thick red felt-tip.
And a big red ‘X’ had been drawn across Marina’s face.
CHAPTER 10
When in trouble, seek sanctuary.
I decided we should go to Aynsford.
Marina had become very agitated on seeing the newspaper cutting. She was sure that we were being watched and I agreed with her. She packed a few clothes whilst I rang Charles.
‘What, now?’ he asked. Charles was old-fashioned in that his house telephone stood on a table in the hallway and I could imagine him glancing at his long-case grandfather clock. It would have told him that it was after ten thirty, almost his bedtime.
‘Yes, Charles. Now, please.’
‘Physical or mental problem?’ he asked. He knew me too well.
‘Bit of both,’ I said. ‘But it’s not me, it’s Marina.’
‘Marina?’
‘I told you about her last week,’ I said. ‘She’s Dutch and beautiful. Remember?’