Comment by kelnos

The latter implies that suicide just happened to the person, like they got hit by a bus.

The former correctly attributes the action to the person who killed themselves. Certainly the motivations and causes that drive people to suicide are complex, but ultimately it is a choice the person makes.

"Committed" is perhaps not the best word, since it's associated with crimes (and suicide is not a crime in many places anymore), but it's at least more active.