Investigators who have interrogated Tamerlan Tsarnaev’s surviving brother, Dzhokhar Tsarnaev, say the two were motivated by the U.S. wars in Iraq and Afghanistan. On Wednesday, federal officials said that despite earlier reports, Dzhokhar was unarmed when he was detained inside a boat where he had hidden to escape a city-wide manhunt. Police had opened fire on the boat before he was detained. Speaking at the memorial for Sean Collier, an MIT police officer allegedly killed by one of the brothers last week, Vice President Joe Biden called the two “knock-off jihadis.”

Vice President Joe Biden: “They can never defeat us. They can never overthrow us. They can never occupy us. So why? Why? Whether it’s al-Qaeda central out of the Fatah or two twisted, perverted, cowardly, knock-off jihadis here in Boston, why do they do what they do?”