(CNN) -- The body of actor James Gandolfini has been returned to the United States, a family friend said Monday.
A charter flight to Newark, New Jersey, on Sunday night carried the body of the "Sopranos" star, Michael Kobold said.
An autopsy determined his death was the result of a heart attack, Kobold said.
A funeral service for family and friends is scheduled for Thursday in New York, Kobold said. It will be held at The Cathedral Church of St. John the Divine in Manhattan.
Gandolfini, 51, died last week while on a working vacation in Rome. He arrived there with his son, Michael, the day before he died.
"Jim was happy, he was healthy, he was doing really fine," Kobold said recently. "He was on vacation with his son. He has an 8-month-old daughter. Everything was going great. I just spoke to him on Father's Day."
The same day Gandolfini died, he had visited the Vatican and dined with his son, the family said. After he returned to his room, his son alerted hotel staff that he was not answering knocks on the bathroom door.
Hotel staff broke down the door to get to him and called an ambulance, said Tiziana Rocca, head of a film festival the actor was planning to attend.
Gandolfini was in Italy to receive an award at the Taormina Film Fest in the Sicilian town of Taormina.
Instead of the award ceremony, the festival paid tribute to Gandolfini's lifetime achievements.
The actor shot to fame on the HBO drama "The Sopranos." In the widely successful series, he played Tony Soprano, a tough New Jersey crime boss. He also appeared in various movies, including "Zero Dark Thirty" and "Killing Them Softly."