Background: A bound state of the Λnn system has been reported, but at least three theoretical papers question the existence of such a bound state. Purpose: We address the alternative question of whether there might exist a resonance in the Λnn system, using a rank-one separable potential formulation of the Hamiltonian. Methods: We examine the eigenvalues of the kernel of the Faddeev equation in the complex energy plane using contour rotation to allow us to analytically continue the kernel onto the second energy sheet. The model Λn interaction is fitted to the Λp scattering length and effective range. Results: We follow the largest eigenvalue as the Λn potentials are scaled and the Λnn continuum is turned first into a resonance, and then into a bound state of the system. Conclusions: Because a change in the strength of the Λn potential of as little as 5% will produce a Λnn resonance, we infer that an experiment of the H3(e,e′K+)nΛ3 type at JLAB could be used to constrain the properties of the Λn interaction.