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.

Police in the Dominican Republic say the FBI has joined the search for a 20-year-old University of Pittsburgh student who went missing nearly a week ago while on spring break.