Theravada POV, rebirth is determined by
rebirth-relinking consciousness upon dissolution of the current
life. It means, the state of mind upon death is important as it
will determine the next destiny as we all have our almost infinite
stores of Akusala (bad/unwholesome) kamma, all competing to enter
the mind-door at death.
Unfortunate people who commits suicide (mostly) are in bad state
of mind, maybe too distraught with loss, grief-stricken, extremely
depressed or in anger. These unwholesome state of mind, will most
likely enter the mind door upon death and invokes the dying
consciousness, hence rebirth-linking consciousness.
However, not necessarily they will appear at woeful places, as
appearance in such places need also the supportive kamma. It’s best
we don’t speculate too much on people who die committing suicide,
but to pass our merits to them when we perform dana or other
meritocarious deeds.
It’s a good blessing to be able to pass away peacefully, as our
state of mind will most likely be wholesome, therefore increasing
the chances for rebirth in good places.