I am a research software engineer for a behavioural science research group at a university, currently trying to help my academics with recruiting for and running psychology and economics experiments online. As part of this I have been reviewing the literature in the field and have come across a very useful paper. In the paper, a link is given for the source code and raw data collected by the authors, however the link is dead - it looks like the domain name registration has lapsed.
After a cursory internet search, it seems that the author whose domain the materials were hosted on has left academia and now works in industry. A co-author still works in academia though. Both are listed as corresponding authors on the publication, though the latter is marked as "principal corresponding author".
In a case like this, who should I approach to ask if accessing the data/source code is still possible? Should I try to contact the author who no longer appears to work in academia, but who seems to have been the one to initially host it? Or should I try to make first contact with the "principal corresponding author" who does still appear to be based at a research university?