In heart-wrenching detail on Facebook and in a family blog, the story of Kevin San Roman’s battle against leukemia unfolded over three years. Then, he died.

Relatives and younger brother Lucas continued writing about their grief and a little cousin’s struggle to beat a brain tumor.

Over several years, both young men — who purportedly lived in Spain — attracted hundreds of Facebook friends from schools in South Miami-Dade while advocating cancer causes and tugging at the heartstrings of teachers, parents and students. Several teens became their online girlfriends, trading text messages, talking by phone and planning to meet in person.

But the San Roman family was all a lie. The long-running charade unraveled in July as police and prosecutors — alerted by a suspicious Kendall teacher whose daughter had fallen for Lucas — launched an investigation.

The probe revealed that an imposter from Doral concocted the details of cancer treatment, accounts of doctor visits and untimely deaths of phantom characters. Family photos, and ones of supposed cancer-stricken relatives, were stolen from the web.

Hundreds of young people were duped, comforted because each “brother” had dozens of mutual friends from St. Brendan, Lourdes and Coral Reef high schools.

Ultimately, investigators could not bring criminal charges. The imposter never physically abused anyone. And the person behind the fake Facebook pages and blog removed them before prosecutors could preserve them.

The saga, nevertheless, is a cautionary tale of deception in the digital age, where the meaning of friendship has been twisted by the mere click of a mouse.

“These predators are using Facebook and getting away with it,” said Maria Masters, 49, whose daughter became embroiled in the drama. She says she hopes her family’s experience will raise awareness about Facebook fakes. “Your kid may think they know someone, but if they haven’t met them in person, they may not exist.”

Friend request

For Kaitlin Masters, now 19, it started in January 2011 with a simple Facebook friend request.

In his early 20s, Kevin San Roman looked like an Abercrombie & Fitch model. He boasted scores of “mutual” male and female friends from her school, St. Brendan High in Westchester.

He lived in Spain, son of a plastic surgeon. He had a sister in Sunny Isles Beach. His cousin, Katy, had been diagnosed at just 6 months old with brain cancer.

And Kevin himself was battling leukemia. The family kept a blog: “Kevin and Katy’s Cancer Journey.”

The blog, which stretched back to July 2009, detailed everything from Kevin’s platelet and white blood-count to the side effects of chemotherapy.

“You have to be very knowledgeable about cancer to put all this on a blog,” said Masters, herself a breast cancer survivor. “It was very, very believable.”

Over the months, Kevin exuded optimism. Treated at Mount Sinai Medical Center, the cancer was in remission. He hoped to one day become an oncologist.

Charming, witty and sensitive, Kevin had studied in Miami and had at least three long-term romances with girls. On the phone, his voice was peculiar — a result, he said, of the chemotherapy.

One of his girlfriends, now 22, said that Kevin figured out where she lived by looking at a Facebook photo. One night, he texted her: “I was outside your house but didn’t have the courage to knock. So I sat on your bench and drank a McFlurry.”