MAKHACHKALA, Russia During a six-month visit to his Russian homeland last year, Boston bombing suspect Tamerlan Tsarnaev spent his time reading novels and reconnecting with family, not venturing into the shadowy world of the region's militants, his parents said.
But investigators are now looking into a range of suspected contacts Tsarnaev made in Dagestan, from days he may have spent in a mosque in the capital to time spent outside the city, with a relative who is a prominent Islamist leader recently taken into custody by Russian authorities.
The emerging details of his time in Dagestan have not fundamentally altered a prevailing view among American and Russian investigators that he had been radicalized before his visit. However, there have been reports that he sought out contact with Islamist extremists and was flagged as a potential recruit for the region's Islamic insurgency.
It remains unclear to what degree his months in Russia, which were punctuated by punishing attacks between the police and insurgents, may have changed his perspective. But an official, who said he was not in a position to confirm or deny reports of Tsarnaev's contacts, said it appeared that he intended to link up with militant Islamists but left having failed.
"My working theory is that he evidently came here, he was looking for contacts, but he did not find serious contacts, and if he did, they didn't trust him," said Habib Magomedov, a member of Dagestan's anti-terrorism commission.
Investigators in Russia also are looking into Tsarnaev's interactions online and exploring whether he and a Canadian-born militant, William Plotnikov, may have been part of a larger group of Russian-speakers who mobilized online, under the auspices of an organization based in Europe, a law enforcement official said.
Unearthing what investigators have learned became more difficult two weeks ago when President Vladimir Putin said that, "to our great regret," Russian security services were unable to share operative information on Tsarnaev and his brother, Dzhokhar, with American officials. The police in Dagestan have said Tsarnaev was not under surveillance.
Since then, an official from the Anti-Extremism Center, a federal agency under Russia's Interior Ministry, confirmed for the Associated Press that operatives had filmed Tsarnaev during visits to a Makhachkala mosque whose worshippers adhere to a more radical strain of Islam, and scrambled to locate him when he disappeared from sight after Plotnikov was killed in a counterterror raid. An official from the same unit told the newspaper Novaya Gazeta that Tsarnaev had been spotted repeatedly with a suspected militant, Mahmoud Mansur Nidal, who was killed shortly thereafter in a counterterror raid.
What is certain, however, is that investigators are looking into the time he spent with a distant cousin, Magomed Kartashov, founder of a group called Union of the Just, a Salafi religious organization that promoted civic action, not violence.
Kartashov, whose relation with Tsarnaev was first reported in Time magazine, was recently detained by police after taking part in a wedding procession that flew Islamic flags.
Agents from the Federal Security Service visited Kartashov last Sunday in a detention center to question him about his relationship with Tsarnaev, focusing on whether the two had shared "extremist" beliefs, said Kartashov's lawyer, Patimat Abdullayeva.
Abdullayeva said that her client had discussed religious matters with his younger relative but that he had been a moderating influence on the younger man, whose views seemed to be more radical.
"Magomed is a preacher, he has nothing to do with extremism," she said.
As head of the Union of the Just, Kartashov has led demonstrations protesting police counterterrorism tactics, which are often brutal, and calling for the establishment of Islamic law, or sharia, in the region. At a rally in February, he aligned himself with anti-government forces in Syria, saying, "We do not want secularism, we do not want democracy, we want the law of Allah," according to the newspaper Nezavisimaya Gazeta.
The time Tsarnaev spent with Kartashov may offer the first firm clues to his thinking during that period.
Five men who spent time with both of them told Time that the younger man was apparently interested in radicalism well before he came to Russia and that they tried to dissuade him from supporting local militant groups. Kartashov's group is mainly known for protests, including one targeting the United States late last year, after the release of the film "Innocence of Muslims."
Shakrizat Suleimanova, Tsarnaev's aunt, said the men were third cousins and remembered each other from their childhood and regularly spent time together last summer, but added that Kartashov was "no kind of extremist and spoke against any kind of killing."
Meeting with Salafi groups would not in itself signify extremist views, and in recent years Dagestani authorities have allowed a gradual expansion of Salafi organizations. Authorities regularly scrutinize such organizations, however, in their attempt to identify militants.