I'm no expert in these cases (not a lawyer either) but from what I know, your friend is the only one to blame why he's in jail.

When he left for vacation and failed to come back, he not only abandoned his job, he also escaped the responsibilities he was supposed to face when he had that car accident.

You tell us that after 4 and a half years, everything is forgotten?

I think you need to consult the/your embassy for this...

Only my opinion....
What you are is what you have been, and what you will be is what you do now. - Buddha