C# Reflection with Picture Box

I want to do the following:

          string WhoIsTheSender="pictureBox1";

        switch (WhoIsTheSender)
        {
           case "pictureBox1":  
                    pictureBox1.Image = Properties.Resources.ledOff; 
                    break;
           case "pictureBox2":  
                    pictureBox2.Image = Properties.Resources.ledOff;
                    break;
            //....until case "pictureBox64":  pictureBox64.Image = Properties.Resources.ledOff;
                    break;
        }       

Is there a possible way to make it much shorter? How do I use reflection?

string WhoIsTheSender="pictureBox1";
        WhoIsTheSender.Image = Properties.Resources.ledOff; //in this specific example WhoIsTheSender="pictureBox1";            

Thank for the helps in advance!