Authorities in the Dominican Republic are turning up the heat on the Iowa man who was the last person to see University of Pittsburgh student Sudiksha Konanki before she went missing — grilling him into the early morning hours on Sunday.

Although authorities consider Joshua Riibe a “person of interest” in the case, he has not been charged or formally accused of any wrongdoing. However, his passport has been confiscated to prevent him from leaving the country.

According to a source involved in the investigation, Riibe, a former high school wrestler with a strong build, has been "cooperative" with authorities.