In 2005, among the ranks of a shadowy organization reigning the streets near MacArthur Park in Los Angeles, a business decision was made. Building on an already highly profitable drug-dealing operation specializing in crack cocaine, they would tap a new revenue source -- extorting the vendors that crowd the streets each evening, selling everything from clothes to pirated DVDs to electronics, supplementing a hardscrabble existence. That was the enterprise described by federal prosecutors in a racketeering trial against the Columbia Lil Cycos, a group they depicted as one of the most ruthless and lucrative cliques of the 18th Street gang. To refuse payment -- at first $10 or $20, later climbing to $50 -- meant to invite the ire of the clique’s enforcers, they alleged. The business decision led to bloodshed in September 2007 when an 18-year-old tasked with gunning down a defiant vendor accidentally shot to death a 3-week-old infant. The baby’s death triggered a large-scale crackdown on the clique that culminated with a two-month trial that began this March. On Friday, a Los Angeles jury convicted four of the clique’s members of federal racketeering charges for participating in the gang’s operations. One defendants, Javier Perez, also was convicted of conspiracy to commit murder and conspiracy to kidnap for luring the baby’s shooter down to Mexico and attempting to strangle him, to avoid the heat on the clique after the baby’s killing. The three others, Eduardo Hernandez and twins Vladimir and Leonidas Iraheta, accused of being the gang’s muscle, were also convicted of drug-trafficking charges. Among the witnesses at the trial were the vendor, who lived despite four gunshot wounds, and the gunman, who survived the gang’s attempt on his life. “It was a group that rose to power through the willingness of its members to act ruthlessly for the gang,” Assistant U.S. Atty. Kevin Lally told jurors in closing arguments. “This is a case about a criminal enterprise, the CLCS, and those that did its bidding.” The jury deadlocked, however, on charges involving an older murder that prosecutors attributed to the gang: the 2001 slaying of college student Jose Barajas Jr., whom gang members allegedly mistook for a rival gangster. The defendants face up to life in prison when they are sentenced in September, according to prosecutors.