Terrorism prosecutor: Bombing suspects wanted to make statement

Dzhokhar and Tamerlan Tsarnaev lived in the U.S. for about a decade after leaving their native Chechnya, a heavily Muslim region in southwest Russia. Tamerlan Tsarnaev, 26, was killed in a shootout with police early Friday, and authorities locked down Boston and surrounding areas as they searched for his 19-year-old brother.

Although authorities haven't determined if the brothers entertained any radical notions before they came to the U.S., Jim Candelmo, a former assistant U.S. attorney in Raleigh, said people shouldn't look at them as either home-grown or international terrorists because such labels are increasingly irrelevant.

"You don't have to go to a classroom or facility setting or cross international borders anymore (for terror training)," Candelmo said. "All of the information you need is right there (on the Internet) at your fingertips."

The FBI on Thursday evening released images of the bombing suspects captured on video cameras near the marathon finish line shortly before Monday's explosions, which killed three and wounded about 170.

"I couldn't believe how utterly calm, almost cavalier, they appeared (on the footage)," Candelmo said.

The fact that the brothers didn't try to disguise themselves before the crime and never tried to escape is a red flag for law enforcement about the type of criminal they were dealing with, he said.

"They're not about preserving themselves. They're not about getting away with it. They're about something different," he said.

Setting the bombs off near the finish line instead of somewhere else along the marathon course – or somewhere else in Boston where a large number of people were congregated – also is key to determining the brothers' motivation, according to Candelmo.

"Obviously, they wanted to make a statement," he said, noting that he was struck by the fact the a row of flags from various countries was next to where the first bomb exploded.

Candelmo praised the quick work of investigators to identify suspects in the bombing and said they will now comb through the brothers' phone and financial records and interview their family and friends to determine who else might have been involved in the bombing.

He, for one, said he believes the brothers are part of a terror network, noting the length of time Dzhokhar Tsarnaev remained on the run after his brother's death.

"To plan this, to stay there locally in the area afterward," he said, "there must have been some type of support."