  The pole trajectory of Efimov states for a three-body $\alpha\alpha\beta$
system with $\alpha\alpha$ unbound and $\alpha\beta$ bound is calculated using
a zero-range Dirac-$\delta$ potential. It is showed that a three-body bound
state turns into a virtual one by increasing the $\alpha\beta$ binding energy.
This result is consistent with previous results for three equal mass particles.
The present approach considers the $n-n-^{18}C$ halo nucleus. However, the
results have good perspective to be tested and applied in ultracold atomic
systems, where one can realize such three-body configuration with tunable
two-body interaction.
