Russian authorities had alerted the FBI that Tamerlan Tsarnaev, an ethnic Chechen and legal US resident who authorities say set the bombs with his younger brother, may have been radicalised while visiting Russia's southern region of Dagestan.
In the first congressional hearing into the deadly double bombing, lawmakers expressed outrage, particularly at a lack of intelligence sharing that kept Boston officials in the dark about potential terror threats. "My understanding is that at no time prior to the bombing did any member of Massachusetts state police or the [intelligence-gathering] fusion centre have any knowledge of the Tsarnaev brothers," Boston police commissioner Edward Davis told members of the house homeland security committee.
He and another official, Massachusetts undersecretary of security Kurt Schwartz, testified that the intelligence information was never shared with their departments.
Davis said he learned about Tsarnaev's background only after the youth was killed in a shootout with police following the bombings.
Republican Michael McCaul, the committee chairperson, sounded incredulous about US officials' inability to streamline data sharing.
"My fear is that the Boston bombers may have succeeded because our system failed," he said.
"The idea that the feds have the information and it's not shared with the state and locals, defies why we created a department of homeland security in the first place," McCaul added.
Such shortcomings will resurrect concerns about the "stove-piping" of intelligence data within US agencies – a problem highlighted in the aftermath of the failed attempt by Nigeria's Umar Farouq Abdulmutallab, the so-called "underwear bomber", to blow up a commercial airliner on Christmas Day 2009.
Former senator Joseph Lieberman, who worked at length on improving US security in the wake of the September 11 2001 attacks, testified on Thursday, and called the latest missteps an "aggravating omission".
"Why didn't they involve local law enforcement, who could have stayed on this case?" Lieberman asked.
"How do you explain it? People are imperfect."
Democrat Sheila Jackson Lee expressed similar concerns, saying "it still baffles all of us" that Tsarnaev's Russia trip did not trigger heightened intelligence gathering on the brothers.
Republican Jeff Duncan said the lingering confusion over who gets placed on which counter-terrorism databases – including the main database known as Tide, as well as a no-fly list, and other classified catalogues – was compounding the problem.
"We're struggling to connect the dots with regard to possible terror suspects in various US threat databases," Duncan said. But Davis said it was too early to start pointing fingers.
"I'm not ready to vilify anybody at this point in time, but there are questions that need to be answered and I'm looking forward to the reviews of what occurred so that we can get to the bottom of a lot of different questions," he told reporters.
'They do not forget'
In his written testimony Davis called for heightened security at public events, including surveillance technology, to help thwart terror attacks, but cautioned against "police-state" tactics.
"Images from cameras do not lie. They do not forget," Davis said as he highlighted the role a Boston business's security video played in identifying the Tsarnaev brothers as suspects.
But he warned that the use of increasingly sophisticated surveillance technology should not be "intended to chill or stifle free speech".
"In the future we will need to deploy more assets including technology, cameras, undercover officers and specialised units," he said.
"This need, however, must be balanced against the protections of our constitutional liberties. I do not endorse actions that move Boston and our nation into a police state mentality, with surveillance cameras attached to every light pole in the city." – AFP