Investigators aren't saying where the Boston Marathon bombings suspects Tamerlan and Dzhokhar Tsarnaev got the guns they allegedly used to attack law enforcement, killing an MIT campus officer and wounding a transit officer.
"The ATF is working very closely with the FBI to track those weapons down and determine where they came from, but again, it's an active investigation," Boston Police Commissioner Ed Davis told Morning Joe Tuesday.
NBC News has confirmed that the Tsarnaev brothers did not have gun permits or petitions to carry weapons. Dzhokhar Tsarnaev, 19, is underage to carry a firearm under Massachusetts law.
On Jansing & Co. Tuesday, Rep. Patrick Meehan, R-Penn., a member of the Homeland Security Committee and a former federal prosecutor.
"This is probably not a circumstance, in which this is going to be very effective at being used as a means to heighten the call for higher registration of weapons. Eighty percent of the guns that criminals use do not come to them by virtue of purchasing them and registering them," Meehan said. "In fact, more than 40 % come out of the black market." Those statistics, Meehan said, might back up arguments against greater gun regulations.
A USA Today poll shows support for new gun laws dropping below 50%.
"The farther you get away from Newtown, you will see less public fervor," Huffington Post's Amanda Terkel said on Jansing & Co.
Last week, proposed legislation to expand background checks for gun purchasers failed in the Senate, and efforts to ban high-capacity magazines and assault weapons have stalled as well. Families of the victims of December's mass shooting in Newtown, Conn., have vowed to continue the fight to pass new gun laws.
"If they [Tamerlan and Dzhokhar Tsarnaev] got [their guns] on the black market, then the NRA will probably claim it bolsters their argument that criminals don't follow laws so it's kind of pointless to even pass new gun control laws. But, if they went across state lines, if they went to New Hampshire, Vermont, or Maine and purchased guns in a private sale, then that's exactly the kind of sale that a universal background check bill would try to stop," said Alex Seitz-Wald of Salon.