.- The family of Indiana priest Father Christiaan Kappes and the Archdiocese of Indianapolis are concerned about his apparent disappearance in Greece.

“We are praying for the well-being of Father Kappes and his family and for Father Kappes’ safe return to the United States,” the archdiocese said Oct. 4. “We are concerned that Father Kappes’ family has not been able to contact him in recent days. The archdiocese also has not been able to locate him.”

The 37-year-old priest, a native of Indiana, had been engaged in doctoral studies in Athens on Orthodox Christian theology at the request of the Vatican.

Greg Otolski, executive director of communications for the Archdiocese of Indianapolis, told CNA the circumstances of the priest’s disappearance are still unclear.

“There are a lot of questions and no answers,” he said Oct. 4.

The priest’s family members said the priest’s translator and close friend Ioanna Lekakou was involved in a major dispute over her family’s inheritance. Fr. Kappes told them someone had threatened to kill her and he believed he too had become a target.

“He told my dad on Monday, ‘If you don't hear from me in 12 to 24 hours, I'm dead,’” Father Kappes’ sister Nadia Charcap told Fox 59 News.

The priest reportedly sought help from the U.S. Embassy but did not receive the assistance he needed. A priest in Greece said he dropped off Fr. Kappes and his translator at the Athens airport, from which they planned to fly to Indianapolis on separate flights.

It is not known whether either made it on a plane.

The Archdiocese of Indianapolis said it has been in contact with the apostolic nuncio to the United States, who is investigating the matter. U.S. Sen. Richard Lugar (R-Ind.) is also investigating.

Fr. Kappes was participating in a pilot program set up between the Vatican and the Greek government to study Greek Orthodox theology in hopes of overcoming the historical divisions between the Catholic Church and the Greek Orthodox Church, the archdiocese’s newspaper The Criterion reported in 2009.