Bobby Chesney blogs about the charges in the imminent federal indictments against Tsarnaev.

The trickiest jurisdictional hook is in  18 USC 2332f:

This is another capital charge, and another complicated statute with many moving parts.  The core coverage of the statute is for bombings in public places, which is applicable here, but there is an additional complicated jurisdictional requirement where the attack is in the US . . . 2332f(d)(3) does further limit the statute’s reach in that particular scenario, specifying that when jurisdiction is predicated on (b)(1)(F) there must also be an impact in interstate commerce.  Satisfied here, I think.

2223f(d)(3) provides:

(3) offenses committed within the United States, where the alleged offender and the victims are United States citizens and the alleged offender is found in the United States, or where jurisdiction is predicated solely on the nationality of the victims or the alleged offender and the offense has no substantial effect on interstate or foreign commerce.

So did the bombing affect interstate commerce? I saw one estimate that the cost of shutting down Boston for one day due to the manhunt was in the neighborhood of $333 million. That says nothing about the cost to the people killed and injured by the explosion, to the surrounding businesses, and other costs.