Laplacian of reciprocal of square of r

Question

What is $I=\nabla ^2 \left (\dfrac{1}{r^2}\right )$ where $r$ is the radial coordinate? As $\nabla ^2 \left (\dfrac{1}{r}\right )=-4\pi \delta(r)$ does it mean that $I\propto \delta(r)$? Given $r^2=x^2_1+x^2_2+x^2_3+x^2_4$.