أَوْ وُجِدَ فِي الْمَعْرَكَةِ وَبِهِ أَثَرُ الْجِرَاحَةِ،
Translation: or one found on the battlefield with signs of injury,
Athar al-jarah is evidence of injury. Being located at the battlefield and having signs of fatal injury are two elements of the formulation.
The location and physical evidence are considered together; mere presence without supporting evidence should not be treated as an automatic finding.