And then there was the toxic waste. For every pound of meth manufactured, five or six pounds of toxic waste were produced, and it was usually disposed of in the yard or surrounding area. The toxic waste and fumes produced can seep into ground water as well as run off into fields. Anyone living near where meth manufacturing had occurred could suffer serious illnesses related to chemical toxicity. Chemicals permeated into the water, ground, carpeting, walls in the home, and into the air.

And the really bad news for Aaron Goodwin, the Manchester solicitor, was that once a home had been exposed to the toxic chemicals from methamphetamine production, it had to be condemned, and the clean-up costs were tremendous. Mr Goodwin would need deeper pockets than he’d imagined, if he was ever going to be able to live his rural dream, with horses in the paddock and a swimming pool in the yard.

So what about the workers? Users of methamphetamine put themselves at enough of a risk, but tweaking crystal meth was as dangerous as manufacturing it in the first place. Makeshift laboratories put their operators at risk of death or injury from explosions and the poisonous fumes produced during the cooking process.

The list of ingredients was totally horrifying. The chemicals used to make methamphetamine included iodine, drain cleaner, paint thinner, battery acid, anti-freeze, and cat litter. Some of those substances were akin to nerve agents. And not forgetting one of the vital elements in the recipe – pseudoephedrine, the active ingredient from several over-the-counter cold remedies.

Today, specialists were being sent in to Pity Wood Farm wearing protective clothing and breathing apparatus. Officers in white coveralls, green gloves and overshoes, carrying oxygen tanks had replaced the SOCOs and the anthropology team, not to mention the CID officers protected by nothing more than a pair of latex gloves. Warnings had been set up that the site was extremely hazardous. Exposure to some of the volatile toxic chemicals that had been found could have carcinogenic effects.

And DI Hitchens was right – like everything else, the instructions for methamphetamine production were readily available on the internet.

The meth factory at Pity Wood had already closed before the drug had been re-classified to a Class A substance. Not that the threat of a life sentence was much of a deterrent to the people who ran meth factories. They relied on not getting caught, and the amount of money they could make justified the risks – especially as the risk was mostly to other people, ignorant workers who just did as they were told. And, of course, they hadn’t been caught. Not yet.

Cooper looked up and saw Hitchens pacing the room. Instead of retreating to his own office, the DI was fretting about every member of his team who might have been exposed to risk.

‘The women buried at Pity Wood Farm, sir?’ said Cooper. ‘Nadezda Halak, and the other woman who died – how might they fit into the scenario?’