Gillard picked up a series of different transparent polythene evidence bags, each of which was labelled with date and place of discovery, and the date of testing. At the right-hand end of the lower shelf was a large bag with several items in it. Gillard read the label which showed that they had been retrieved from Mrs Roy’s office in Slough, and were initialled by DI Mulholland. Inside it were several smaller polythene evidence bags: toothbrush, toothpaste, Nivea moisturiser, a roll-on deodorant, and a small bottle of some essential oil with a label written in what looked like an Indian script.

‘Well done, Claire,’ Gillard said.

‘Yeah, I sent off a swab of the oil to Yaz for his wife to do the thallium test,’ Hodges said.

‘What about the toothpaste?’

Hodges laughed. ‘She’s hardly gonna get poisoned by Colgate is she?’

‘Test it anyway.’ Gillard opened the bag containing the moisturiser and unscrewed the lid. He gave it a sniff. ‘It would be quite possible for someone to put in here, wouldn’t it? Then she rubs it on, and it gets through the skin.’

Hodges gave an expansive shrug. ‘What are all these tests for anyway, sir? We’ve got a suspect, he’s been charged with the murder. I don’t understand what we are doing with all this stuff.’ He gestured at all the evidence bags.

Gillard scowled at the junior detective. ‘There are other things going on here that I’m afraid I can’t share with you. But I need you to take seriously the idea that there was a poisoning attempt.’

‘I’ll send them all for tests if you want.’ He made it clear he thought it a complete waste of time and money.

‘You were already told to do that. It says here in DI Mulholland’s notes. But you thought you knew better, didn’t you?’ Gillard held up the bag, which contained a brand-name roll-on deodorant. He squinted at it, and manoeuvred the item within the bag.

‘What have you found there, sir?’ Hodges asked. He watched as Gillard rapidly undid the polythene bag’s seal, then hesitated, looking around.

‘What are you after?’

‘Plastic gloves,’ Gillard said. ‘I want two pairs on before I touch this.’ He found a packet of gloves in a drawer by the entrance to the warehouse, and put on two pairs.

He returned to find Hodges squinting into the evidence bag. ‘What have you found? I can’t see anything.’

‘Let me show you,’ Gillard said, holding the bag up. ‘The deodorant has been on its side and leaked into the bag.’

‘Okay,’ Hodges said, warily.

‘Why would it leak, Colin?’

‘It’s full of liquid, on the roller maybe, and seeps under the cap.’

‘They’re designed not to do that.’ He carefully retrieved the roll-on from the bag. ‘Don’t touch it. But if you look carefully at the seam where the two halves of the plastic moulding of the case join, there is a tiny hole.’

‘You must have good eyes,’ Hodges said, peering at the deodorant. ‘I can’t see anything.’