D4vd Explains Idea for His Alter Ego Who Murders People, in Resurfaced Clip

D4vd says the music video for his most famous song brings to life an idea he had ... about a detective solving murders his alter ego commits ... and he's comparing himself to Brad Pitt in "Fight Club."

The singer -- who is facing questions over his connection to the body of a teen girl found dead in his car -- explained the bloody and violent imagery in the "Romantic Homicide" music vid ... he says it introduces his alter ego, Itami, a name that is Japanese for "pain."

D4vd sat down with Mahogany back in March to talk about the visual world he builds with his music videos ... and his comments are being scrutinized now that police say they found missing teen Celeste Rivas' decomposing and chopped-up body in the trunk of his Tesla.

He says he was writing his own anime series at one point ... about a detective with an evil alter ego that commits murders ... which the detective then has to solve. D4vd says the alter ego is "basically an agent of chaos."

D4vd says the evil version would pop up at random moments like Tyler Durden in "Fight Club" ... and he says "Romantic Homicide" allowed him to express those ideas in the music video.

In the interview, D4vd says, "I put that all on screen, and me and Itami had a great time just like chopping it up and getting to kind of merge creative ideas on the entire thing."

D4vd's also got some interesting lyrics and animations in his "Rehab" music video, which was released on Celeste's 13th birthday.

His alter ego cuts the arm off a petite brunette female character after he sings ... "It's too much for me to handle, handle / White rose petals, broken hearts and bloody sandals / Bodies stacked on top of another / Good undercover / Too bad for each other now."

Celeste's missing-person poster notes she was last seen wearing Hello Kitty sandals.