The closure conjecture for nonclosed maximal totally geodesic submanifolds

Let $(M,g)$ be a closed Riemannian manifold with negative sectional curvature, of dimension $n\geq 3$. An immersed totally geodesic submanifold $N$ in $M$ is maximal if it is not contained in another proper closed immersed totally geodesic submanifold. The closure conjecture. If $M$ contains a maximal totally geodesic immersed submanifold $N$ which is not closed, then the closure of $N$ is an immersion of a totally geodesic locally symmetric space of rank $1$ in $M$. This is presented as a generalization of the corresponding theorem for nonclosed totally geodesic submanifolds; the source does not state that the conjecture has been resolved.