It depends what level of proof you are looking for. If you mean irrefutable proof, I don't think you will find as much. If you mean indications, here are a few:
The verse in Koheles (8:1) says
חכמת אדם תאיר פניו
a man's wisdom lights up his face. This has been understood (see, for example, here) to refer to that which there is a light in a person's face, which comes from his Neshama, and when the person dies, there is a noticeable ashening of the face as a result of the departure of the Neshama.
Similarly, the Maharal (Derech HaChaim ch. 3) explains the Gemara in Shabbos 151b:
ר' שמעון בן אלעזר אומר תינוק בן יומו חי אין צריך לשומרו מן החולדה ומן העכברים אבל עוג מלך הבשן מת צריך לשומרו מן החולדה ומן העכברים
A one day old baby does not need to be guarded from weasels and mice, but [the giant] Og king of Bashan, dead, does need to be guarded from weasels and mice
that this natural fear animals have of man, which ends with his death, comes from the G-dly spark (the soul) within the person.