(CNN) -

What happened in Cairo today sends a chilling message to any journalist covering Egypt: If you speak to a group whose message the government wants suppressed, you can be prosecuted and jailed for it.

In other words, you can be imprisoned for doing your job.

The lengthy sentences against three Al Jazeera journalists -- Peter Greste, Mohamed Fahmy and Baher Mohamed -- convicted of aiding terrorists and spreading false information have shocked and angered many around the world.

And inside the Cairo courtroom, those closest to the accused were left reeling.

"Well, to be perfectly honest, my mind was blank. There was total disbelief," Peter Greste's brother Mike told me. "I can't comprehend the decision made by the court today."

Mike Greste said the convicted trio were lead out of their cage shortly after the sentences were handed down.

With no way to speak to his brother, he says he put his hand on his heart and raised a fist into the air to give Peter some encouragement.

Condemnation of the court's ruling was swift. A Human Rights Watch researcher, Heba Morayef, tweeted that even deposed president Hosni Mubarak would never have jailed prominent journalists in this way:

It now appears as though no amount of political pressure or public outrage has swayed authorities in Egypt who -- after ousting President Mohamed Morsy of the Muslim Brotherhood last year -- have made it clear they will not tolerate dissenting voices.

There is of course the fact that the three work for Al Jazeera, which is funded by the Qatari government and seen as supportive of the Muslim Brotherhood. Some have said the journalists are being used as pawns in a political rivalry between Egypt's new rulers and Qatar.

The network issued a statement shortly after the ruling, saying the verdict "defies logic, sense, and any semblance of justice."

The prosecution case against Greste, Fahmy and Mohamed included material from a story that was filmed when none of the defendants were even in the country. On another day, footage of a trotting horse was used by the prosecution. On yet another, music by Australian singer Gotye was introduced into evidence.

All this would be genuinely hilarious if it hadn't ended in the sentences read out today by the judge. Verdicts that mean the three journalists were led back into custody once again as prisoners in the new Egypt.

As for what the future may hold, Mike Greste told me his brother will appeal the sentence.

"We have to maintain support for Peter and continue to fight for his innocence."

As for us journalists, should we be concerned that if we do our duty -- in other words if we speak to all sides when reporting from Egypt -- we too will be tried, convicted and jailed for a crime we did not commit?