SP Pitch

[SRW]

I'll try to explain with words what happened last night...might be hard to picture but I'll try.

ASA Coed SP game. Pitcher on the pitching plate with left foot. Takes a small step to his right with his right foot, then goes down on his right knee. So now his right foot is out to the side, and his knee is under his torso. Both his right foot and knee are on the ground. The left foot is still in contact with the pitching plate. At the moment his knee touches the ground, he releases the ball.(pitcher is right-handed).

Goofy-looking as heck, hard to describe.

Legal or Illegal pitch? And why?