Liz Halloran

As investigators combed through evidence in the deadly Boston Marathon bombings, seeking both motive and perpetrator, we turned Tuesday to a security expert for guidance on how the investigation may be unfolding.

Bryan Cunningham, a former CIA officer, assistant U.S. attorney and deputy legal adviser for the National Security Council, served in both the Clinton and George W. Bush administrations. He is now a senior adviser at the consulting firm the Chertoff Group, co-founded by former Homeland Security Director Michael Chertoff.

Rand Paul going to one of the top historically black colleges in the U.S. and trying to school students on who founded the NAACP?

Priceless.

Rand Paul going to one of the top historically black colleges in the U.S. and trying to make a case for his Republican Party as a historic and continuing defender of the civil rights of African-Americans?

Not boring.

And, judging from the reaction the Kentucky senator received Wednesday at Washington's Howard University, less than persuasive.

Thousands of supporters will descend on the U.S. Capitol on Wednesday to call for legislation that creates a path to citizenship for immigrants in the country illegally.

Sound familiar?

But this time, unlike in 2007 and 2010 when immigration legislation died in Congress after similar demonstrations, proponents of an overhaul say politics has swung inexorably toward their side.

"I've been working on this issue for more than a decade, and it feels unstoppable now," says Ana Avendano, director of immigration and community action at the AFL-CIO.

Two county prosecutors fatally shot in Texas. Colorado's top prison official gunned down. And a dozen more members of the U.S. justice community — ranging from police to judges — victims of targeted killings since the beginning of the decade.

What's going on?