Case statement

I have a case statement that detects what key has been pressed on a keyboard,
at the moment i have four different cases for four different letters,
how would i go about making a case that changes depending on what key is pressed,
for example, i have letters falling down the screen, and i need it so that if there is an R on screen the user has to press an R etc…

at the moment im using,

override function keyDownHandler(e:KeyboardEvent):void {        //override any other key operations
    switch (String.fromCharCode(e.keyCode)) {                    //switch statement checks letter pressed in
        case 'T' :                                                //if T is pressed
            for (var i:uint=removeNum; i<clip; i++) {
                hitTarget = this.getChildByName("letter"+i);    //gets the correct letter clip
                if (hitTarget.hitTestPoint(leftSmall.x, leftSmall.y, true)) {    //if its hit the perfect circle
                    removeChild(hitTarget);        //remove the clip
                    removeNum++;                //add one to numebr removed
                    small=true;                    //small true
                    score+=10;                    //add to the score
                    energy.gotoAndPlay(energy.currentFrame-40);    //increase energy
                    perfectClip.gotoAndPlay(2);                    //play the perfect clip
                    return;                                        //exit

any suggestions at all?