Last December, the 32-year-old New Yorker quit his job, packed his bags and took off on an adventure by motorcycle, chronicling his exploits through the Americas on A New Yorker Travels, his blog.
"I don't think there's anyone who, on their deathbed, every lamented pursuing a passion, pursuing a dream," he wrote last month. "In fact, I imagine in fact it would be quite the opposite."
Then, just days after that post, on Jan. 25, he vanished without a trace after checking out of a bed and breakfast in Michoacán, Mexico.
He went missing in a region where fighting has broken out between a powerful drug cartel and local vigilantes, and his final text messages referenced the danger. His mother, who originally feared he had gotten into an accident, has had a change of heart.
"We now believe he has been taken by someone and is being held captive and is waiting for someone to find him," his mother Devert, 66, of Pelham, N.Y., tells PEOPLE.
Courtesy Jackie Burrell
Devert's friends and family have created a Facebook page, the hash tag #helpfindHarry via his Twitter page and an online petition to help find him.
A seasoned traveler – "I've slept on a beach in Rio, a bench in Barcelona, a street in India, a cave in Vietnam, a hammock in Laos," he wrote on his blog – Devert got his wanderlust from his late father, says his mother, who last spoke to her son on Jan. 23.
"We had a very bad connection," she says. "He said he'd be going somewhere out of range and he'd be getting back to me in a few days.
When he didn't call her on Jan. 29, his father's birthday, she began to get concerned. "He always calls me," she says.
That weekend she contacted the American Embassy in Mexico City to report him missing.
Michoacén turned out to be much more dangerous than he expected, according to a text he sent to his girlfriend, Sarah Ashley Schiear, on Jan. 25.
"Just got an hour and a half long escort out of some area it was too dangerous for me to be," he wrote.
"Apparently there's another military escort waiting for me in some other town," he wrote. "I'm running way late because of the crazy military stuff ... hopefully get a chance to talk to you tonight when I (hopefully) finally arrive."
He was headed to a beach in Zihuatanejo, where the last scene of The Shawshank Redemption, one of his favorite movies, was filmed, his mother says.
While Devert believes her son is still alive, she also knows he believes that any danger he faced was well worth the adventure.
"He's always told me, 'It's not how long you live, it's how you live,' " she says. "And he's told me that the law of averages will not be on his side."