Polish police have issued an urgent appeal for information following a violent domestic incident resulting in one death and one injury. A man is in custody after allegedly fatally stabbing his father-in-law and seriously wounding his mother-in-law. Authorities released a photograph of the suspect to aid in the ongoing investigation and potential further leads. The incident occurred within a domestic setting, though specific details regarding the location and motive have not yet been released. The injured woman is receiving medical treatment, and her condition is currently unknown. Police are continuing to investigate the circumstances surrounding the attack and are urging anyone with information to come forward. This case is being treated as a homicide investigation.