Dance me to the end of me

Sal Mineo and Juliet Prowse perform a captivating, albeit disturbing erratic dance in the cult film Who Killed Teddy Bear? (1965). They dance to It Could Have Been Me.
The sequence begins at 1:39. It is a little tale within a tale, told only in movement to, and fighting against, the music. It is a story of Sal Mineo's character's final and finite disintegration.
Unfortunately, there is no soundtrack of this film, and It Could Have Been Me has never been recorded independently. It seems to be credited to Al Kasha. Singer? It could have been Sal Mineo.