In order to maintain the relationship with Castro, "Claudia" avoided asking direct questions about Fidel Castro or politics within Cuba. The conversation between the two became romantic, with Castro encouraging "Claudia" to visit him in Cuba, Dominguez said.
Tony repeatedly sent pictures of himself for "Claudia" and on several occasions the pair chatted for up to five and six hours at a time.
As the son of Fidel Castro, Tony Castro told "Claudia" he did not travel with any bodyguards on a daily basis but did carry guns with him and said he moved freely throughout the country with access to currency and communications, Dominguez said.
During the course of their online courtship, Dominguez said, Castro described for "Claudia" a lavish lifestyle out of the reach of most Cubans, who, under the country's communist rule, have restrictions to Internet access, travel and income.
According to Dominguez, Fidel Castro's son said he has constant access to the Internet, a BlackBerry set up for wireless and international phone calls and a penchant for Apple computers.
"Most Cubans make $20 a month; I don't know how he can afford a $2,700 computer," Dominguez told ABC News.
The young man's access to Internet and communications are in stark contrast to what's available for most Cubans.
ABC News consultant in Havana Marc Frank said that while owning a computer is now legal on the island, "only one in every eight to 10 homes even has a phone, let alone a computer, let alone Internet."
For most Cubans, "BlackBerries don't exist," Frank said.
Castro's son, however, "had access to the Internet all the time" and was "sometimes driving and chatting with me on his BlackBerry," Dominguez told ABC News.
Castro also sent "Claudia" pictures from his extensive travels around the world. In one photo, Castro poses outside the Olympic village at the 2008 Beijing games, a trip he took with the country's baseball team.
According to Dominguez, on Jan. 29, while Tony Castro was on a state trip to Russia with his uncle, Raul Castro, he chatted on his BlackBerry with "Claudia" into the early hours of the morning.
He even sent "Claudia" a photo of himself from Moscow, just hours before he was to attend a bi-lateral meeting, Dominguez said.
Although "Claudia" usually kept her chats with Castro focused on romantic topics, Dominguez told ABC that he was able to use "Claudia" to get insight on Fidel Castro's health, information he then shared with officials in Miami.
"On Jan. 15, in Miami, the rumors were huge that his father was dying," Dominguez said. "That night, he spent over an hour and a half talking to me. To me, that meant that his father was alive and that proved to be correct."
Dominguez said he is determined to share what "Claudia" has learned about the Castro family with the Spanish language media and Cuban communities of Miami.