'It depends on the pressure. If there's the possibility of financial or moral disgrace he might not want his male child to see that or live with the knowledge of it. He would see killing him as a favour. Men have killed their entire families because they think they have failed them and that it's better nobody survives bearing their name and its shame.'

'But you have your doubts?' said Calderón.

'Suicide, whether it's a pact or not, is rarely a spontaneous thing and there are some spontaneous elements to this crime scene. First, the door was not securely locked. Consuelo Jiménez had called to say that Mario had fallen asleep so they were sure he wasn't going to return, but they didn't double lock the door.'

The door was shut, that was enough.'

'If you're about to do something unnatural you would put yourself behind locked doors to make absolutely certain there was no possibility of interruption. It's a psychological necessity. Serious suicides normally take full precautions.'

'What else?'

'The way everything has just been left here: the phone, the chocolates, the slippers. There seems to be a lack of premeditation.'

'Well, certainly on her part,' said Calderón.

That is a point, of course,' said Falcón.

'Drain cleaner?' said Calderón. 'Why would you take drain cleaner?'

'We may find there was something stronger than drain cleaner in the bottle,' said Falcón. 'The reason? Well, he could be meting out punishment to himself… you know, cleaning himself of all his sins. There's also the advantage of it being noiseless and, depending on what else he's taken, irrevocable, too.'

'Well, that does sound premeditated, Inspector Jefe. So there are both spontaneous and planned elements to these deaths.'

'All right… if they were lying on the bed together holding hands, dead, with a note pinned to his pyjamas then I'd be happy to treat it as suicide. As it stands, I would prefer to investigate the deaths as murder before deciding.'