Over Chuseok, the three-day Korean holiday celebrating the fall harvest, 78-year-old Choi Du-ho journeyed with his family to one of the northernmost cities in South Korea.

There, Choi prayed for his father. But unlike the countless other Koreans across the country bowing at graves and altars adorned with food offerings for their ancestors, Choi did so not in his hometown but at the doorstep of North Korea — and for a man who may still be alive.

Choi was one of more than a hundred people who arrived at Imjingak in Paju on Tuesday morning to pray for loved ones