According to what I have seen , most people go back to Iran to meet their family .
But Iranian regime put pressure on families of people which they are active against Iran, in foreign countries to force them to go back to Iran , then they can arrest them and torture them and some times that you may have seen in the news Kill them.
I think the same has happened to this developer.
I remember there was a time which most of my friends were arrested , just because they were really active on the web (on any subject even computing and network not just political activity)
It is written here that he was a developer and an author of the largest Iranian pornographic websites. (I cannot believe it because according to Persian Wikipedia , he studied in the best University of Technology in Iran called Sharif University which means that he could get fund from any University in the world to continue his studies and that was what he did , He traveled to Canada to study in the Victoria university but when he heard that his father is sick he went back to Iran to see his father but the Iranian Cyber arrested him)
His wife claimed that he just developed a software which he didn't know about where it was about to used. And as usual that a developer put his name in a file inside the software package he wrote his name in a file without the knowledge of where its going to be used.
I'm an Iranian developer living in the UK , I heard he was arrested because of developing Iranian porn website.
I'm not sure about it , but this is what I heard in the news while I was In Iran.
check this blog for more info:
http://peoplewithoutnation.wordpress.com/