Los Angeles (CNN) -- The description of a Los Angeles street gang seems right out of Hollywood.
In the square mile between the University of Southern California and an edge of downtown where an NFL stadium is being planned, a group of thugs called Harpys or Harpys-Dead End gang runs extortion rackets, "taxes" businesses, robs students and threatens to kill snitches, federal prosecutors allege.
Authorities arrested 18 defendants Thursday named in three federal indictments as part of 2 ½-year investigation called Operation Roman Empire, a play on words referring to imprisoned gang kingpin Danny Roman, spokesman Thom Mrozek of the U.S. attorney's office said.
In all, the indictments name 29 defendants. Five are fugitives or have yet to be fully identified, officials said. The remaining defendants are already in state custody on other charges, prosecutors said.
Roman, now serving a life sentence without parole, allegedly controls Harpys and more than a dozen Latino gangs across south Los Angeles, but he is not charged in the indictments, prosecutors said.
Roman is a member of the Mexican Mafia, and he allegedly gave orders from prison to his daughter and her husband, both of whom were arrested Thursday, prosecutors said.
The couple visited Roman in Pelican Bay State Prison in northern California, and their orders allegedly included collecting "taxes" on businesses and gangs under the threat of violence and murder, prosecutors said. The money was allegedly funneled back to Roman in prison.
The 18 defendants arrested Thursday were to be arraigned later in the day, prosecutors said.
Among those regularly extorted were vendors at an indoor Spanish-speaking marketplace called the Alameda Swap Meet, which is in the territory of another unit allegedly controlled by Roman called the 38th Street gang.
The indictment alleges that Roman's gang empire distributed methamphetamine, cocaine, crack cocaine and heroin; murdered a gang member who owed a debt; committed armed robbery against three USC students; and plotted to kill a state court witness against a member of another gang, prosecutors said.
Roman's daughter Vianna Roman, 37, of Los Angeles, and husband Aaron Soto, 40, of Los Angeles, relayed the imprisoned leader's orders to a "shot caller" and other high-ranking members of Harpys, prosecutors alleged.
The shot caller also allegedly enforces collection of taxes from other Latino gangs under Roman's control and allegedly delivers orders to the other gangs on drug sales and the use of violence, prosecutors said.
During the investigation, officials seized about 8½ pounds of methamphetamine, a half-pound of heroin, a pound of cocaine, 23 pounds of marijuana and 22 guns, prosecutors said.
During Thursday's arrests, two more firearms were seized and 10 children were removed from several residences by the Los Angeles County Department of Children and Family Services' Multi-Agency Response Team, prosecutors said.
All except one defendant face a maximum sentence of life in prison if convicted.