Q: What is the migration story of the Boston Marathon bombers? How did they reach the United States and get radicalized?

—Mike Cooper, Atlanta

A: Tamerlan Tsarnaev was born in the former Soviet Union in 1986 and younger brother Dzhokhar Tsarnaev was born in Kyrgyzstan in 1993.

Their family lived in Kyrgyzstan and Dagestan (a Russian republic on the Caspian Sea) before their parents — Anzor and Zubeidat — and Dzhokhar arrived in the United States on tourist visas in 2002.

Tamerlan remained in Kyrgyzstan with an uncle.

Anzor and Zubeidat applied for asylum and Tamerlan later joined the family in the United States.

Tamerlan grew more religious and heard a “voice inside his head,” the Boston Globe reported.

The FBI investigated Tamerlan and his mother for three months in 2011, and Tamerlan was added to terrorist watch lists.

Tamerlan began reading more about Islamic militants and traveled to Dagestan, where he stayed for six months in 2012, the Globe reported.

He was more devoted when he returned to the United States and had two outbursts at a mosque in Cambridge, Mass. He was asked to leave the building after the second one in January 2013.

Dzhokhar, who was struggling academically at the University of Massachusetts Dartmouth, apparently began “spending more time” with Tamerlan, the Globe reported.

They read an article titled, “Make a Bomb in The Kitchen of Your Mom,” the paper wrote, in an Al Qaeda online magazine.

The Boston Marathon bombing killed three and injured 264 others on April 15, 2013.

Tamerlan was killed during a shootout with police on April 19, 2013, and Dzhokhar received a death sentence last year.

Andy Johnston with Fast Copy News Service wrote this column. Do you have a question about the news? We’ll try to get the answer. Call 404-222-2002 or email q&a@ajc.com (include name, phone and city).