Citing officials briefed on the investigation, ABC News reported Friday Tsarnaev -- who was killed three days after he and his brother allegedly carried out bomb attacks that killed three people and injured 270 others at the marathon finish line -- went to Dagestan intending to contact militants but did not join them.
The investigation into Tsarnaev's background suggests he was mostly self-radicalized before he went to Dagestan but may have been further radicalized once there. He does not appear to have been affiliated with any international terror organization, such as al-Qaida, or controlled by anyone in Dagestan, said the officials, who spoke on condition of anonymity.
Investigators have not identified a contact in Dagestan or any specific motivation for the bomb attack, the report said.
Investigators learned Tsarnaev was close to Mahmud Mansur Nidal in Dagestan. Nidal joined a militant group, but there is no evidence Tsarnaev joined as well.
Nidal was subsequently killed by police.
Tsarnaev's younger brother, Dzhokhar, was arrested April 19 in Watertown, Mass., the day after Tsarnaev was killed in a shootout with police.