Ian’s death

Y’all I need help, when Ian fell from the bell tower, was he killed straight away? Or did he actually shot himself in the head( I can’t remember) and if he was already dead ( if I remember correctly garret said his body was decaying a week or something) so who was texting Melissa ? Was it A? Cause at first I thought it was Wren but she had his number saved cause they talked on the phone.