He did. That follow through is found in the Freeh Report pgs 66 - 79 and it wasn't him who failed to follow through.
So Paterno knew that Sandusky was showering with little boys, and knew that there were witnesses to some pretty bad events, and he brought it to the attention of his bosses, but they didn’t follow through. So Paterno did his part, right?
And in spite of knowing this.... he continued to allow Sandusky to have full access to the PSU athletic facilities through 2011.
And poor old Joe was just a naive old man who didn’t even know these types of acts were possible. Riiiiiiiight.