From: Rabbi Moshe Sofer
To: Rabbi Yaakov Weiler
The Chasam Sofer rules that the wife of R' Gadil, who went missing in a severe flood, may be permitted to remarry. He bases this on the cumulative weight of facial recognition testimony by a Jewish melamed, non-Jewish mesiach l'fi tumo testimony, a corroborating identifying mark confirmed by the mother, and the lenient positions of Tosfos, the Rosh, the Maharit, and the Maharival regarding b'diddemi and ishtahi. He directs the local beis din to convene three judges to formally issue the heter in accordance with SA EH 17:39.
Source: Shu"t Chasam Sofer EH I §88