Madison parents fear for son missing in Europe

Two Madison parents are searching for their son who is currently missing in Europe. Jon Luskin, the 25-year-old son of Susan Stone and Allan Luskin, has been off the grid since June 22.

Jon is a Middleton High School graduate and was travelling with family on a European vacation. He and his mother parted ways in Austria, when she returned to Madison for work. Jon continued on via train to Slovenia, where he had planned on hiking in Triglav National Park. From there, he was supposed to continue on to Croatia, Greece, then home to Hong Kong, where he teaches chemistry.

That's when Stone received the call no parent ever wants to hear from Josh, Jon's roommate in Hong Kong.

"The roommate calls and says are you seated? And you go cold, and your heart drops down into your belly, and you go oh God," she said.

Stone and Luskin have been working with Slovenian police, the U.S. Embassy in Slovenia, and the FBI to try to retrace Jon's steps.

"They can confirm that he was in a youth hostel just outside Liblijana on the 22nd before he went missing," Stone said. That was the last cell phone ping from Jon's phone.

"We're really fearful that he went into the national park and never came out," said Luskin.

Jon's parents and his three siblings only hope for his safe return, and for the family to be reunited.

"They're just fun when they're together," Stone said of the siblings. "It's one of those things that when you see them they all get along, and they kind of rib each other."

While Stone and Luskin are staying optimistic, they are also considering a different reality.

"Our hearts are breaking," Luskin said.

"You wake up in the middle of the night and the first thing you think about is Jon," Stone said. "And sometimes you go back to sleep, and sometimes you don't."

Stone and Luskin hope to be getting on a flight to Slovenia on Sunday or Monday, where they plan on meeting with members of the U.S. Embassy as well as officials from the national park to try to find their son.

NBC15 reached out to Sen. Tammy Baldwin's office for comment: "Ms. Stone contacted our office about her son and we informed the State Department of the situation, including the U.S. Citizen Services Emergency Assistance Unit, the U.S. Embassy in Vienna, Austria and the U.S. Embassy in Ljubljana, Slovenia on Ms. Stone’s behalf, and confirmed that the State Dept. is in contact with the family. We are standing by to be helpful to the family in any way we can."

NBC15 also reached out to the U.S. Department of State - Bureau of Consular Affairs. A spokesperson said that they are generally unable to share details about individual cases with the media. In an earlier report to ABC News, The State Department confirmed it is working with local authorities to find Luskins, who currently works as a teacher in Hong Kong.