Iowan Joshua Steven Riibe told prosecutors he and Sudiksha Konanki were hit by an intense wave and were swept out to sea.
The Loudoun County Sheriff's Office in Virginia said U.S. investigators interviewed a person of interest at length.
International authorities have issued a global alert for the missing University of Pittsburgh student. Authorities in Sudiksha Konanki’s home county of Loudoun, Va., requested the alert.