“American Idol” alum Caleb Flynn is under arrest for allegedly murdering his wife … but it looks like he’s the one who called 911 and claimed someone broke into their Ohio home and shot his wife, Ashley.

Listen to Flynn’s 911 call, obtained by TMZ … he’s emotional and borderline hysterical as he tells the dispatcher there’s blood everywhere and gunshots to his wife’s head.

Flynn says the door to the garage is wide open and their kids are in the house asleep. He tells the dispatcher his wife’s face is “white as a ghost.”

He’s still on the call when cops arrive … and you hear him talking to officers.

As we reported … Flynn was arrested Thursday by the Tipp City PD and booked into the county jail for murder, felonious assault, and tampering with evidence, according to official records. He posed for a mug shot with no expression on his face.

TMZ also obtained dispatch audio from the incident, and at one point you hear a dispatch officer report there’s a woman who was shot in the head and is not responding.

Law enforcement says Flynn shot 37-year-old Ashley using a 9mm semiautomatic handgun and then staged the crime scene.