  The status of our investigation of low-energy $K^+$Xe collisions in the Xenon
bubble chamber DIANA is reported. In the charge-exchange reaction $K^+Xe \to
K^0 p Xe'$ the spectrum of $K^0 p$ effective mass shows a resonant enhancement
with $M = 1539 \pm 2$ MeV/c$^2$ and $\Gamma \le 9 MeV/c$^2$. The statistical
significance of the enhancement is near $4.4\sigma$. The mass and width of the
observed resonance are consistent with expectations for the lightest member of
the anti-decuplet of exotic pentaquark baryons, as predicted in the framework
of the chiral soliton model.
