So this may not have been a suicide. A few years ago the pilots of an A330 trying to recover from a stall crashed because the terrified copilot kept his hand pushing down on the joystick and the pilot didn't see it. Which was the right thing to do at first (to get out of a stall, step one is to push down. But if you keep pitching down you will crash). Unlike the yokes on Boeing, Embraer or Bombardier airliners, the joysticks on the Air Bus aircraft starting with the A320 (not including the nearly extinct A300 and A310), do not move in unison.
So let's say the A320 hit an unusual air pocket, or had an engine malfunction, or some other incident and stalled. It could have been an exact repeat of what happened to Air France. Even if that was not the case, unless we have a recording of the copilot saying "Hahaha, now I'm going to kill everyone" while the pilot stepped out of the cockpit, suicide is impossible to prove. You can have instances of suspected suicides but they might be due to seizures or other problems occurring at a critical moment in flight.
There were two crashes attributed to suicide in recent years, aside from 9/11, one involving EgyptAir and the other involving SilkAir. In both cases, Egypt and Indonesia have rejected the NTSB opinion that it was suicide due to the Muslim cultural taboo against this. And maybe they have a point; it could have been unintentional suicide caused by pilot confusion. There have been new studies showing engine bleed air, which is what you're breathing on everything except a Boeing 787, is not as healthy as was previously thought, particularly for flight crew who breathe it daily.
But until we get the official report even speculation is dangerous. Although I do with it was the NTSB and not the BEA or the German or Swiss authorities handling this. The BEA in prior decades and the Germans botched a number of investigations for political reasons, such as the Air Inter A320 crash and in the 1950s the Munich air disaster involving a British European Airways Airspeed Ambassador, which was wrongly attributed to icing rather than runway contamination. But hopefully they've improved and we will get a good report. I am a big fan of the NTSB though; they consistently focus on improving safety, preventing accidents and not finding a culprit for the masses to hate on. And because they're separate from the FAA which performs day to day inspection, regulation and enforcement, they are quite impartial; they have on many occasions blamed the FAA. If you care about aviation safety, you want impartial investigators who have no ties to the police, who people aren't afraid to talk to.