The passport of Joshua Riibes, an American linked to the disappearance of a University of Pittsburgh student, has been confiscated by Dominican authorities as part of an ongoing investigation, his attorneys told NBC News.

St. Cloud State senior Joshua Riibe has remained in his hotel room under police surveillance when not questioned at the police station, his parents said.

The authorities said they have interviewed a man they believe was the last person to see Sudiksha Konanki, 20, before she disappeared on a spring break trip to Punta Cana.