Who is Paul Whelan, the US man arrested in Russia on spying charges? The facts emerging about Whelan have so far produced a curious figure.

Moscow -- Of the many questions around Paul Whelan, the former United States Marine arrested in Russia on spying charges, one puzzling aspect is his use of Russian social media.

Whelan had a long-standing enthusiasm for Russia, traveling there previously at least twice, according to his twin brother, and talking online about his efforts to learn Russian. For a decade, Whelan also maintained an account on the Russian social media site VKontakte, using it to reach out to ordinary Russians he often didn’t know to try and befriend them. Those he contacted were surprised by it, saying they couldn’t understand why he had written to them.

"He didn’t want to know anything specific," Alexander Buzov told ABC News, saying Whelan had never explained why he had added him on Vkontakte roughly 9 years ago. "He just started the dialogue with 'Hello! How are you?'"

Of the several friends on Whelan’s VKontakte account reached by ABC News, all of them said he had contacted them out of the blue. Whelan, they said, had simply struck up conversation, making small talk about their travels and sending greetings on Russian holidays.

"We didn’t know each other. About a year ago he simply sent a request," Pavel Laponov, a former soldier in Bryansk said by telephone, adding he had found it "very strange."

Whelan's account has lost around 10 friends since his arrest was announced. The 55 remaining contacts are almost exclusively young men (there appears to be only 3 women) and the majority appear to have some kind of connection to the military posted on their page.

All of Whelan's contacts who spoke to ABC News said they had been very surprised to hear of Whelan’s arrest, saying he had seemed simply an unusually friendly foreigner who was interested in chatting with Russians and that he had never sought any sort of significant information from them. He had written in English and Russian that contained mistakes, with one contact saying they thought he was using an online translator.

Whelan’s outreach adds to the curious portrait that has been built up of him so far.

Currently director of global security for the large American car parts supplier, BorgWarner, Whelan had been discharged from the Marines in 2008 for bad conduct, after being found guilty of stealing $10,000 while on a tour of duty in Iraq. In the mid-1990s he had served as a part-time police officer in Chelsea, Michigan.

Born in Canada to British parents with Irish descent, Whelan later re-settled in Michigan, according to his twin brother. That family history gave him the three other citizenships that he was unexpectedly revealed to possess last week, when it was found Britain, Ireland and Canada were all also seeking to provide consular assistance to Whelan, in addition to the U.S.

Now 48, Whelan’s interest in Russia appears to date from well before this most recent trip to Moscow, which his family have said was to attend a wedding of an old friend in the Marine Corps to a Russian woman.

Whelan’s first trip to Russia was as early as 2006, a vacation he described in an interview to a Marine publication. On a now defunct personal site, he described meeting some Russians and taking excursions around the country.

“Having grown up during the Cold War, it was a dream of mine to visit Russia and meet some of the sneaky Russians who had kept the western world at bay for so long,” Whelan wrote on the site.

Those Russians he befriended online said he had never said much beyond generalities. Buzov said Whelan had talked about the weather, trips and his service in Iraq, but nothing substantial.

Whelan, Buzov said, had asked him to meet once on a visit to Moscow but he had “politely refused because I didn't understand his motivation.”

“I thought that he was a fan of military issues and a very sociable person," Buzov said. “At his age, what else does he have left to do except chat with different people on social media.”

Laponov, the former soldier, said Whelan had only asked him about countries he had posted holiday photos from.

"He wrote, 'Oh, those are very good countries,' something like that. He just sent a few ratings about them, but I didn’t answer because, well, he’s an unknown person to me," Laponov said.

Whelan’s social media has attracted interest in part because of unverified reports last week on a Russian news site. Russia has still not provided any information on what Whelan is accused of, but the only allegations to have emerged publicly so far appeared have appeared on the site, Rosbalt, which is known to have ties to the security services.

Rosbalt cited an anonymous security services source, who said Whelan was arrested after receiving a memory card with a classified list of Russian operatives.

Rosbalt also claimed authorities accused Whelan of trying to recruit Russians as intelligence sources using internet forums. The site asserted Whelan had spent 10 years trying to befriend Russians online who were likely to have access to classified materials and then, after years of internet chat, meeting them in Russia to try to cultivate them over drinks.

The Rosbalt reports have not been confirmed or verified in anyway and former U.S. intelligence officers have expressed skepticism, suggesting instead that they are fabricated to frame Whelan.

"This has all the hallmarks of a Russian KGB-style setup," Dan Hoffman, a former CIA agent who served as a station chief in Moscow, told NPR on Friday. The allegations may have been tailored from Whelan’s social media profile, and Hoffman suggested, the FSB had likely been tracking him for years.

In any case, former U.S. intelligence officials have said Whelan’s court martial would almost certainly have excluded him from being selected as a U.S. operative. They also noted that the CIA rarely sent agents into Russia without diplomatic cover because the risks of arrest were too high.

“If he was involved in anything related to intelligence, it was a massive uncoordinated screw up,” John Sipher, who used to run the CIA’s Russia operations, told ABC News last week.

Some former U.S. officials have suggested Whelan's arrest could be retaliation for Maria Butina, the Russian gun rights activist who pleaded guilty last month to trying to infiltrate American conservative political circles as an illegal foreign agent.

One explanation why Whelan reached out to Russians with military connections is that they shared his background. Most of Whelan’s social media friends also appeared to have already graduated from military academies and some now had civilian jobs. Military service also is compulsory in Russia and studying at a military academy doesn't guarantee a career in the armed forces.

All of those reached by ABC News said Whelan, in any case, had never asked them about their military service.

Laponov, who said he left the military in 2012, suggested Whelan might have added him because he had visited the U.S.

Laponov would not give details of his military experience, but in photos dated from 2012 on his social media account in which he appears in uniform with an assault rifle, Laponov identified himself as a member of Russia’s chemical and biological protection troops.

The other Whelan contact, Buzov, said he was a civilian but refused to give more details, saying that he worked in housing utilities. His social media photos, however, include one from several years ago in which he is wearing a military cadet’s uniform.

Some of Whelan's other social media friends contacted by ABC News declined to comment. One account, for Vasily Razumovsky, showed many photos of a man in combat gear and a post linking to an elite paratrooper school in Ryazan. Two days after ABC News wrote to Razymovsky's account, it transformed into one for a woman called Tamara Matveeva, wearing a negligee, and accompanied by other nude photos and the relationship status “actively searching". The many military-themed posts from before the change though remained on the page.

Whelan’s twin brother, David, has said his brother always sought to make friends in foreign countries when he was traveling and as an avid tourist had made many friends over the years.

“And so like through his VKontakte page, he knew people and he had plans, I think, to visit some of them. We heard from a friend in St. Petersburg who was disappointed at what had happened and explained that he had hoped to have Paul see his new son. So it's that sort of thing,” David Whelan told the Associated Press on Saturday.