David Prosser: The questions that Rio Tinto must answer

Outlook Now the trial of the Rio Tinto four is over, will one of the world's largest mining companies give a full account of this sensational case? While the proceedings have been ongoing, Rio has been able to avoid saying much in public about the events leading up to the hearings. That defence is no longer open to it.

It's easy to assume the worst about China. Clearly, it looks suspicious that Rio's executives were first charged a few weeks after the collapse of a deal between the mining giant and Chinalco, the state-backed business. And since the Shaghai court sat mostly behind closed doors – not entirely unfairly, given the case concerned commercial secrets – there's no way for observers to come to an independent view about the evidence in the case.

Still, the Rio four pleaded guilty to at least some charges. They may have done so in hope or expectation of lighter sentences, but we can't know that for sure. All one can say is the default option should not be to presume China concocted this case as revenge for the Chinalco "betrayal". We just don't know.

Either way, however, Rio Tinto and the Australian government do not come out of this well. Both have protested about the incarceration of these men – one of them, Stern Hu, is an Australian citizen – but neither have felt strongly enough to be put off signing valuable deals with China. If Rio's executives were the victims of charges trumped up by Chinese authorities, one could understand why they might feel rather abandoned by their employer. The mining company has said that it has been offering them support, but the deal it signed last week with Chinalco to co-develop iron ore resources in Guinea, West Africa, could not have come at a more unfortunate moment. If Rio was really so concerned about the plight of its staff, what was it doing agreeing such an obviously lucrative deal with a Chinese state-backed company just a couple of days before their trial?

If, on the other hand, the Rio four really were guilty all along, why has the miner continued to offer them its support? What did it know about their activities before the Chinese authorities stepped in? And will it continue to employ these men?

As for the Australians, it has always been clear where their priorities lie. For all the outraged talk from Canberra about this case, the government has repeatedly made it clear it regards trade ties with China as a completely separate matter.

It may be that both Rio and Australia came to a measured decision that pulling out of trade deals with China would do nothing to help these men – or even make matters worse. But the suspicion must be that the desire to pursue contracts worth billions of pounds has triumphed over the desire for justice.