This is a simple knowledge check.
The game gave you more than enough clues and multiple hints:
-He would've been the only one at the crime scene who was "unavailable".
-It's specifically mentioned that Saki was interviewed by the police. It couldn't have been Dojima at the time.
(1/2) "Gag" as if the game isn't featuring morning sickness of Heather having a God growing inside of her that she gets a magical birth control pill from her father from & then tries to stomp on the undeveloped fetus so it won't come alive, featuring one of the first puzzles of