Police arrest 13 in videotaped killings in Nigeria October 8, 2012 -- Updated 1602 GMT (0002 HKT) A video on YouTube that shows a mob killing four students leads to arrests Spokesman says investigators have not yet determined why the mob killed the men Some are bloodied, and they have tires shoved over their heads. Read more: Why are Nigerians numb to slaughter? Investigators have not yet determined why the mob killed the men, said Ben Ugwuegbulam, a police spokesman in Rivers State, in southern Nigeria. The attack happened Friday. Mob justice is common in Nigeria, with some people choosing to take the law into their own hands because police are either unresponsive or unwilling to patrol high-risk areas after dark. The posting has drawn comments from some who say that police should have done more to investigate the attack before the video was posted. Read more: Gunmen attack Nigerian university But a plummeting currency has left it unable to compete in the global market. October 4, 2012 -- Updated 1035 GMT (1835 HKT) The search for alien life may seem like a luxurious pursuit, but astrobiology is helping to answer important questions about the human race. October 8, 2012 -- Updated 1409 GMT (2209 HKT) Aged 12, Ishmael Beah was brainwashed, drugged and forced to kill. He tells CNN how using a gun became as normal as drinking a glass of water. October 8, 2012 -- Updated 1706 GMT (0106 HKT) Hugo Chavez is one of the leading leftist figures in Latin America and Venezuela's longest-serving president. But how did he get here? Clashes on the Syria-Turkey border are prompting fears of a regional war. But is Syria a match for the Middle East's strongest military power? October 5, 2012 -- Updated 1643 GMT (0043 HKT) Real Madrid head coach, José Mourinho talks to CNN's Pedro Pinto about his best press conference moments.