TALDYKORGAN, Kazakhstan — The crime was grisly, the trial was bizarre, and the defendant’s confession was widely doubted — but border guard Vladislav Chelakh was convicted Tuesday of killing 14 of his comrades along with a park ranger and sentenced to life in prison.

On the surface, the case against Chelakh appeared strong. Days after the killings in May at a remote outpost along the Chinese border, Chelakh was found hiding in a cave, wearing civilian clothes, and carrying a pistol. Authorities said Chelakh soon confessed.