  New measurement of sub-threshold $K^*(892)^0$ and $K^0$ production is
presented. The experimental data complete the measurement of strange particles
produced in Al+Al collisions at 1.9$A$ GeV measured with the FOPI detector at
SIS/GSI. The $K^*(892)^0$ / $K^0$ yield ratio is found to be $0.0315\pm 0.006
(\mathrm{stat.})\pm 0.012 (\mathrm{syst.})$ and is in good agreement with the
UrQMD model prediction. These measurements provide information on in-medium
cross section of $K^+$ - $\pi^-$ fusion which is the dominant process on
sub-threshold $K^*(892)^0$ production.
