(CNN) Family members of a Southern California-raised psychotherapist arrested in Syria two years ago are asking President Donald Trump to employ his negotiating skills to secure their father's freedom.
Majd Kamalmaz, 61, had traveled from Lebanon, where he runs a mental health clinic for refugees, to Syria, where he planned to check on elderly relatives with health problems and pay condolences following his father-in-law's death, his family said.
He checked in with Syrian officials before the February 2017 trip to make sure he wasn't on any watch list, they say, but he was nonetheless arrested at a checkpoint in Damascus. He hasn't been heard from since.
"Our main goal is to try to reach President Trump to see if he'd be able to take this matter personally and try to bring our father back," Kamalmaz's son, Khalid, told CNN.
The family wrote Trump in October and has received confirmation that the letter reached the White House, but they have not received a response, they say.
Following the onset of civil war, the United States suspended diplomatic ties with Syria in 2012 and expelled its diplomats from the US two years later, but Kamalmaz's daughter says she is confident Trump has the wherewithal to circumvent the icy relations.
"I still believe President Trump has his unique way of negotiating," Maryam Kamalmaz said. "I think he can be successful, and I know that when he puts his mind to something, he gets it done. ... I am very positive about this."
American officials had advised the family not to speak out -- for fear of angering any parties who might determine Majd Kamalmaz's fate -- but after two years without any fortune, they decided to make their appeals public. Their father has diabetes and other health issues, which only exacerbates the family's concern.
"Unfortunately, we haven't received any proof of life -- no voice recordings, no pictures, not a phone call, nothing. We've just received word that he is alive and that's all we know," Maryam Kamalmaz said.
The family has been in touch with the US State Department's presidential hostage envoy, Robert O'Brien -- who Maryam Kamalmaz called "wonderful and very supportive" -- and has worked to leverage contacts both within and outside of Syria.
"We've reached the point now where we need to move up a step. We haven't seen any sort of progress as of yet, and it's time to reach out to the President more directly," she said.
National Security Council spokesman Garrett Marquis confirmed the Kamalmazes' letter reached the White House and said the US government "is in regular contact with the Kamalmaz family to provide support and share information, and remains committed to the safe and expedient recovery of all Americans held hostage or missing in Syria."
A State Department official, too, said the government was in touch with the Kamalmaz family and declined to provide further information, citing privacy concerns.
Daughter Ula Kamalmaz said the last time the family saw her father was in December 2016 for a "small family reunion." He spent time with his grandkids -- of which he now has 13 -- and promised to come back and visit, she said.
Though his children were accustomed to his extensive travels -- to the point that they were at times jealous that they didn't get to spend more time with him -- nothing could prepare them for receiving word he was in Syrian custody.
"When we heard the news, we were quite surprised," Ula Kamalmaz said.
Her father earned a reputation as humanitarian over the years, helping youth in behavioral centers in the United States, war victims in Kosovo and Bosnia and those who suffered during Hurricane Katrina and the Indonesian tsunami.
Most recently, Ula Kamalmaz said, "anyone who needed help was welcomed to his center that he opened up in Lebanon to help refugees with their mental health issues."
The HeartMath Institute, a nonprofit focused on advancing mental well-being, made Majd Kamalmaz one of the first recipients of its Humanitarian Heart Awards.
"He said he was compelled to help Syrian refugees when their mass exodus became a humanitarian crisis. He has been providing stress-management education to refugee children and adults and helped to build intervention and field work teams among other efforts," according to a HeartMath news release.
In a 2016 article on the HeartMath website, published just months before he was detained, Majd Kamalmaz explained why he decided to focus on Lebanon, where UN figures indicate more than 1 million Syrians have sought refuge.
"I made several visits to different countries -- Turkey, Lebanon and Jordan -- to check on the condition of refugees," he said. "I conducted several training programs in these areas, and I've studied where the most need is. I realized really that Lebanon has the most need ... and most of the refugees have witnessed atrocities before fleeing their homes, or having their homes destroyed."
Majd Kamalmaz is "an amazing father" and a "very empathetic, loving" person who has devoted his life to helping others, Khalid Kamalmaz said.
"Ever since he was a young man, he had a passion of helping others," Ula Kamalmaz said. "He couldn't handle seeing someone in pain, so I think it was just a passion of his to help others."