Iran’s foreign minister and the White House both announced that Princeton University graduate student Xiyue Wang was exchanged for scientist Massoud Soleimani.

Brian Hook, the U.S. special representative for Iran, accompanied the Iranian scientist to Switzerland to make the exchange and will return with Wang, a U.S. official told The Associated Press on condition of anonymity. The swap took place in Zurich and Hook and Wang are now en route to Landstuhl in Germany where Wang will be examined by doctors, the official said. Hook is expected to return to the U.S. from Germany alone, as Wang is expected to be evaluated for several days.

“After more than three years of being held a prisoner in Iran, Xiyue Wang is returning to the United States,” President Trump said in a statement released by the White House on Saturday. “The highest priority of the United States is the safety and well-being of its citizens. Freeing Americans held captive is of vital importance to my Administration, and we will continue to work hard to bring home all our citizens wrongfully held captive overseas.”

Secretary of State Mike Pompeo said Saturday that Wang was on his way back to the United States, where he will soon be reunited with his wife and son.

“The United States will not rest until we bring every American detained in Iran and around the world back home to their loved ones,” he said in a statement.

Christine Rollins cared for an elderly couple at their home in the small town of Anahuac.

“Unbelievably tragic. This is a very rare incident, just what little research we have found less than six of these have been reported in the nation,” Chambers County Sheriff Brian Hawthorne said.

Hawthorne said Monday the 84-year-old woman she cared for was waiting for Rollins to arrive on Sunday. The woman went outside and found the 59-year-old Rollins in the front yard between her car and the front door.

Hawthorne says Rollins had a severe head wound and several other injuries consistent with an animal bite. The coroner in neighbouring Jefferson County ruled Monday that Rollins bled to death after an attack by feral hogs. Texas’ KATU2 reported that the medical examiner said the cause of death was “exsanguination due to feral hog assault.

Anahuac is just over 40 miles east of Houston.