MAKHACHKALA, Russia — The parents of Tamerlan Tsarnaev insisted on Sunday that he came to Dagestan and Chechnya last year to visit relatives and had nothing to do with the militants operating in this volatile part of Russia.
But the Boston bombing suspect could not have been unaware of the attacks that savaged the region during his six-month stay.
Tsarnaev, 26, and his 19-year-old brother, Dzhokhar, are accused of setting off the two bombs near the finish line of the Boston Marathon last Monday that killed three people and wounded more than 170.
Three days later, investigators say they killed a university police officer, hijacked a man’s car, and led police on a chase that resulted in a shootout that killed Tamerlan Tsarnaev and led to the capture of his seriously wounded brother.
When the two ethnic Chechen suspects were identified, the FBI said it reviewed its records and found that in early 2011, Russia had asked for information about Tamerlan Tsarnaev. No evidence has emerged to link Tsarnaev to militant groups in Russia’s Caucasus.
Six days after the Boston bombings, marathon runners and spectators around the world sent messages of solidarity to the people of Massachusetts.
Sunday’s London Marathon opened with a 30-second period of silence for the victims, and tributes to the Boston dead and injured were visible all along the course.
Hundreds of people took part in the first marathon ever in the West Bank, which included messages in support of the Palestinian cause but also reflections on Boston’s tragedy.
West Bank participant Demitri Awwad, a Palestinian-American from Fenton, Mich., wore a T-shirt honoring the Boston victims under his official marathon shirt. It bore a picture of 8-year-old Martin Richard, with the boy’s words ‘‘No more hurting people.’’
The Hamburg Marathon on Sunday included a moment of silence and a tribute in German to Martin Richard, along with signs, shirts, jackets, and bracelets expressing support for Boston.
On Sunday the Caucasus Emirate, which Russia and the United States consider a terrorist organization, denied involvement in the Boston attack. But a trip Tsarnaev made back to Russia in January, 2012, has raised questions about his possible involvement with such groups.
His father said his son stayed with him in Makhachkala, the capital of Dagestan, where the family lived briefly before moving to the United States a decade ago. The father had only recently returned.
‘‘He was here, with me in Makhachkala,’’ Anzor Tsarnaev said in a telephone interview. ‘‘He slept until 3 p.m., and you know, I would ask him: ‘Have you come here to sleep?’ He used to go visiting, here and there. He would go to eat somewhere. Then he would come back and go to bed.’’
He said his son went to the mosque for prayers, but would not have come under the influence of radical imams, who he said stay in mountain villages.
Anzor Tsarnaev said they traveled together to neighboring Chechnya. ‘‘He went with me twice, to see my uncles and aunts,’’ the father said.
He said they also visited one of his daughters, who lives in the Chechen town of Urus-Martan with her husband. His son-in-law’s brothers all work in the police force under Chechen leader Ramzan Kadyrov, he said.