A trip to the mortuary was never high on either Greg or Sara's list of things to do, but Dr Robbins' coffee machine made the experience a little better. The two CSIs waited patiently as the coroner passed around the steaming mugs.

'Hmm,' murmured Greg with a smile. 'Almost as good as mine.'

Robbins laughed. 'Almost, eh? You wait until I get my milk frother. Though I may have to wait until the end of the financial year before I slip that request into City Hall.'

Coffees finished, scrubbed and gloved, the three made their way toward Jonathan Marshall's body that lay beneath its white cover on the doctor's slab.

'Well, my preliminary autopsy supports David's suspicions: your victim's head wound was definitely sustained post-mortem.'

Sara bent to examine the contusion for a moment, then spoke. 'Right. So… any indication of cause of death?'

'Not just an indication; tox report came back.' The coroner moved towards his desk and selected a manila file. 'Codeine metabolites were sky high. Drug overdose.'

'Really?'

'Uhuh.'

Greg examined the statistics. 'How was it administered? Pills, or…?'

'That was the odd thing,' continued Robbins. 'I extracted stomach contents, sent them for analysis. Normally in drug overdoses one would expect to find a quantity of undigested pills – potential suicides, if they're serious, don't want to risk messing up, so take more than is necessary for the job, and death occurs before digestion is complete.'

'Like saturation levels,' suggested Greg. 'You put too much sugar in your coffee, after a while it doesn't dissolve.'

'Something like that. Anyway,' said Robbins, 'I found only two codeine tablets, the easy-swallow kind, partially digested. The rest I assume must have been ground up somehow, taken with food. Stomach contents were low viscosity – looked like he had some kind of soup as his last meal – might have made that kind of dose easier to swallow, if you'll excuse the pun.'

'Two tablets…that's the standard adult dose for headache, stomachache,' commented Sara. 'So he must have taken them not long before he died.' She paused. 'Why take two pills when you've just swallowed the rest of the bottle?'

'Unless he didn't know he had,' offered Greg.

Sara nodded in agreement. 'So… you think we're looking at a murder?'

'Or a suicide,' said Robbins.

'What? cried Sara. 'Why? The guy's a successful businessman, retail chain here in Nevada, nice house, doing well for himself. Why would he want to kill himself?'

'Who can tell how the human mind works?' asked Robbins. 'You could try his psychiatrist.'

'Our vic was seeing a shrink?'

'He should have been. Certainly on the kind of dosage he was on.'

'Dosage?' asked Sara, confused. 'What was he taking?'

'Luckily for us, he must have taken his last dose around the same time as he took the two codeine. I found two more pills – one a 40mg propranolol hydrochloride, and one 140mg Efexor capsule.'

'Efexor – that's the trade name for venlafaxine, right?' asked Sara.

'One of the new generation of anti-depressants,' answered Robbins. 'These slow-release capsules tend to be prescribed one, twice daily; 140mg is the largest single dose available. Dosage level depends on a number of factors, not least height and weight. Your vic's 5'9", 150lb; whether he was taking one or two, your vic would have been suffering from fairly serious depression.'

'And the propranolol's a beta-blocker – would have been prescribed for panic attacks, maybe?' suggested Greg.

The coroner nodded. 'I know the circumstances are odd to say the least, but I don't think you can rule out suicide yet. There seems to be some indication he's tried before.' Robbins turned over the victim's left wrist; there were the tell-tale white scars.

'But our vic's on anti-depressants,' argued Greg. 'Why overdose on codeine? Why not the venlafaxine? And why take the anti-depressants anyway if you're intending to kill yourself?'

'Habit, maybe? Not wanting to alert family?' suggested Robbins. 'Who knows. But I can probably help you with the choice of drug. Overdoses on anti-depressants can take a long time to take effect, and particularly with the newer generations of drugs, can require a really massive dose. Codeine, on the other hand – it's readily available, fatal dose isn't too high, and crucially it's quick – you lose consciousness within 10-15 minutes, death can occur within the hour.'

'Second time lucky?' said Sara grimly. 'Still doesn't explain how he ended up at the bottom of the stairs.'