Let $$C_1$$ be the circle of radius 1 with center at the origin. Let $$C_2$$ be the circle of radius $$r$$ with center at the point $$A = (4, 1)$$, where $$1 < r < 3$$. Two distinct common tangents PQ and ST of $$C_1$$ and $$C_2$$ are drawn. The tangent PQ touches $$C_1$$ at P and $$C_2$$ at Q. The tangent ST touches $$C_1$$ at S and $$C_2$$ at T. Mid points of the line segments PQ and ST are joined to form a line which meets the x-axis at a point B. If $$AB = \sqrt{5}$$, then the value of $$r^2$$ is