The alleged gang members are being blamed for a string of violent crimes that stretched from East Palo Alto to San Francisco from September 2012 through December 2013. East Palo Alto's Sac Street and DaVill street gangs allegedly unified against the Taliban, a Menlo Park and East Palo Alto gang, Mr. Wagstaffe said.
The 16 people arrested include one Menlo Park resident, a Palo Alto woman, 11 East Palo Alto residents, two Hayward residents and one from Newark.
The investigation stemmed primarily from five murders and attempted murders, including the Sept. 30, 2012, midday attempted murder of Chris Baker on U.S. 101 in Belmont; the 2012 killing of Stoney Gibson in San Francisco; the 2013 killings of Jonathan Alcazar and Lamont Coleman in East Palo Alto; and the 2013 attempted robbery at Plaza Jewelers in Redwood City.
"The city of East Palo Alto for 20 years has had a serious violence problem," Mr. Wagstaffe said. Although crime has been significantly reduced, residents still live with gang violence and drug trafficking, he said.
Dubbed Operation Sunny Day after the code the persons arrested allegedly used to signify when a murder was successful, the 18-month-long investigation is the most massive case prosecuted by the DA's office in its history, Mr. Wagstaffe said. Investigators served 80 search warrants, used GPS, social media, tapped phones and cell phones, and did "good, old-fashioned hard work and legwork," he said.
The grand jury investigation began in early January and took two months. It is the county's longest, he added. Its members handed down three indictments, including for four separate murders, two attempted murders and "countless other crimes," he said.
All 16 people are in custody, 11 in San Mateo County jail and five others in other jurisdictions. Nine are charged with capital murder with special circumstances: East Palo Alto residents Raymond Bradford, 28 (two counts); Roberto Bustos-Montes, 24 (two counts); Emmanuel Hyland, 25 (three counts); Tyrone Love-Lopez, 21 (two counts); Eric Valencia Vargas, 20 (one count); Marvin Jake Ware, 26 (one count); Miguel Angel Rivera Jr., 23 (one count); Palo Alto resident Nina Mehrnoosh Cragg, 23 (one count); and Menlo Park resident Jerry Coneal III, 19 (one count).
Assistant District Attorney Karen Guidotti, who spearheaded the investigation, said the warfare was about control among the gangs. "It's a question of control, power and respect. One gang member slights another by offending someone, and it becomes a cycle of retaliation," she said.
Deputy district attorneys Jamie Draper and Jordan Boyd were singled out for their work as lead investigators. East Palo Alto Criminal Investigator Sgt. Jeff Liu was also credited with major contributions by that city's interim police Chief Lee Violett.
In 2013, East Palo Alto had eight homicides, Chief Violett said. "Too many young men have died violently, causing loved ones to grieve. ... Our work will not be done until there are zero homicides and our community is safe again," he said.
Several state, local, county and federal law-enforcement agencies worked with the DA's Bureau of Investigations, including Mountain View, Belmont, East Palo Alto and Milpitas police, the San Mateo County Sheriff's Office, the federal Department of Homeland Security, the U.S. Marshals Office and the U.S. Department of Alcohol, Tobacco and Firearms.