Value of KeyPressEventArgs.KeyChar with ctrl key

On a KeyPressEvent I know how to detect when the CTRL key is down, but then I want to get CTRL+[what?].

With CTRL+A, KeyChar = 1, CTRL+B gives 2, etc. What is the best way to detect CTRL+a input?

Here is my code:

private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{
    if (ModifierKeys.HasFlag(Keys.Control))
    {
        Console.Write("(Ctrl) ");
    }
    Console.WriteLine(Convert.ToString(Convert.ToInt32(e.KeyChar)));
}

Entering a, b, CTRL+a, CTRL+b gives:

97
98
(Ctrl) 1
(Ctrl) 2