Kevork Djansezian / Getty Images The Boston Fire Department hazardous-materials team clean the blast site near the Boston Marathon finish line one week after the FBI handed over Boylston Street back to the city in Boston, on April 22, 2013.

Ten years ago the Department of Homeland Security was created to end the lack of information sharing among U.S. law-enforcement and intelligence agencies that had missed the 9/11 terrorist plot. Now it seems that blockages and miscommunications between and within those agencies caused them to miss the Boston Marathon bomb plot last week that killed three people and wounded 176, lawmakers said on Tuesday.

What “is troubling to me [is] that this many years after the attacks on our country in 2001, that we still seem to have stovepipes that prevent information from being shared effectively not only among agencies but also within the same agency in one case,” said Senator Susan Collins of Maine, a top Republican on the Intelligence Committee.

Investigators are still compiling what various U.S. agencies knew about Tamerlan and Dzhokhar Tsarnaev in the months and years leading up to the bombings. Thus far what’s clear is that some agencies didn’t know what other agencies knew. Indeed teams within agencies seemed to not share information with one another.

In a statement over the weekend, the Federal Bureau of Investigation said it was informed in March 2011 by Russia’s security agency, known as the FSB, that Tamerlan was becoming radicalized. The FBI followed up, interviewing Tamerlan and his family and speaking to people at his school, Bunker Community College. It found nothing “derogatory,” sent its findings back to Russia and heard nothing back from the FSB, it said.

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But, the FSB had “multiple” contacts with the FBI and at least one was after October 2011, according to Senator Richard Burr, a North Carolina Republican who sits on the Intelligence Committee. Apparently that information was not shared with the original team that interviewed Tamerlan. Tamerlan, 26, who is believed to be the mastermind behind the marathon attack, was killed in a shootout with police on Thursday.

Then there’s the question of Tamerlan’s travel to Russia last year. The FBI said it did not know that Tamerlan had left the country because he misspelled his name on his exit card. Tamerlan had a U.S. green card and had been applying for U.S. citizenship — a process that had been temporarily blocked because of flags the FBI had placed on his file. (His brother Dzhokhar was granted citizenship on Sept. 11, 2012.)

But Homeland Security Secretary Janet Napolitano testified at an immigration hearing before Congress on Tuesday that her department had been aware of Tsarnaev’s departure. Why this information was not shared with the FBI is an important question, said Senator Lindsey Graham, a South Carolina Republican. “Not to mention, was his name misspelled when he came back?”

Graham said Congress would hold multiple hearings into what happened in Boston and how the brothers became militantly radicalized. In the months after Tamerlan’s return in July 2012, he launched a YouTube page on which he posted radical Islamist videos. “Here’s what I can’t get over,” Graham tells TIME, “how did you miss all this radical stuff on videos? But even deeper: when the bomb went off last Monday, wouldn’t the first thing you’d do if you’re the FBI is to go into the files of everyone we’d interviewed in the Boston area regarding terrorism and see what pops up? How could his name not pop up when they had the photo of the guy? How could they not match the two? So clearly there’s a big problem here.”

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The FBI does have a facial-recognition database of 12 million mug shots, but they have yet to confirm or deny that they ran the images of the Tsarnaev brothers through that database before releasing them on Thursday, asking for the public’s help to identify them. It was the release of their photos that prompted the Tsarnaev brothers’ final bloody rampage that left one police officer dead and another wounded before a manhunt for Dzhokhar that shut down Boston all day on Friday finally ended in his surrender.

Investigators are now not only compiling what various government agencies knew about the brothers, but are also attempting to rebuild both their lives. “They’re leaving no stone unturned,” said Senator Dan Coats, an Indiana Republican, emerging from a classified FBI briefing on the bombings. “Anything relative to these individuals and their lives, what they’ve been doing, whether it’s been here or whether it’s been the trip back to Russia … All of [Tamerlan’s] life is being reconstructed literally day by day, hour by hour.”

For all the apparent missteps, Hill figures are not rushing to judgment. While most Republicans expressed concern about the apparent miscommunications, none were willing to say the FBI dropped the ball. “There’s been some stonewalls and some stovepipes that’s been reconstructed that were probably unintentional, but we’ve got to review that issue again and make sure that there’s the free flow of information,” said Senator Saxby Chambliss of Georgia, the top Republican on the Intelligence Committee. “I can’t say the FBI dropped the ball. I don’t see anybody yet who dropped that ball, that may yet develop.”

Democrats for their part have been even less critical of the FBI. Intelligence Committee chair Dianne Feinstein, a California Democrat, said there are always lessons to be learned after this kind of attack, but that the cooperation in the week since has been exemplary. “What was very clear to me is that this is a long, arduous task, and it makes no sense to speak about any specific part of it right now,” Feinstein told reporters. “But what I know is that I have never in my lifetime seen an effort as positive as this one is in terms of the cooperation and communication between law-enforcement and investigative agencies, and I believe that they will get to the bottom of it eventually.”

Given the confusion that has already emerged, that conclusion eventually may be months, or years, away.