(CNN) -- A few months before the Boston bombings, the suspected mastermind of the terror attack, Tamerlan Tsarnaev, wanted to change his name, a U.S. government official told CNN Wednesday.
Tsarnaev, who was shot and killed in a massive manhunt, made an interesting choice for his new name.
He wrote that he wanted to switch his first name to Muaz, the last name of Emir Muaz -- a Dagestan insurgent fighting in the Caucasus region of Russia, the official added. Muaz was killed in 2009.
Tamerlan Tsarnaev, the big brother of accused bomber Dzhokhar Tsarnaev, filed that request with U.S. immigration on January 23, 2013, as part of his application to become a naturalized U.S. citizen. His brother, Dzhokhar, had already become a naturalized citizen.
"We don't know why," the official says. "There's no evidence why he wanted to change his name."
Whether it was another indication of his radicalization that led to the marathon bombing is speculation, according to the source.
The story was first reported in the Wednesday edition of the Los Angeles Times.
The year before the April 15, 2013, bombing, Tamerlan Tsarnaev traveled to the restive Dagestan region, hoping to meet with Canadian boxer-turned-jihadist William Plotnikov. Russian troops killed Plotnikov in July 2012 while Tsarnaev was in the region. It's unclear whether the two men ever came face to face.
Tsarnaev flew out of Dagestan two days after Plotnikov was killed and investigators have been looking into whether Tsarnaev left because of Plotnikov's death, according to another source briefed on the investigation.
Authorities also have been investigating whether Tsarnaev had any contact with another militant, Mahmoud Mansur Nidal. The 18-year-old was killed by Russian forces in May 2012 during a gun battle in Makhachkala, Dagestan's capital.
As part of the naturalization process, a form requires a signature acknowledging the applicant will swear allegiance to the United State and might be required to serve in the military. Instead, the official says Tsarnaev printed his first and last name, but crossed out "Tamerlan" and changed it to "Muaz."
According to the website www.thinkbabynames.com, the name Tamerlan is derived from Tamerlane, the feared 14th-century warrior who conquered parts of the Middle East and Central Asia. Tamerlane, the name used in the epic Edgar Allan Poe poem, is now more commonly called Timur by historians.