Aaron Michael Hammer appeared briefly in Superior Court, but Judge John J. Cheroske postponed his arraignment to Sept. 23 at the request of the defense. As many as four others were being sought for questioning, Los Angeles County sheriff's investigators said.
Hammer, 24, of Compton, is accused of shooting Yetunde Price, 31, in the chest as she sat in a sport utility vehicle early Sunday with a companion, Rolland Wormley, 28. An assault rifle and shell casings were found at the scene.
Hammer has ties to a Compton street gang although he is not a member, authorities said, declining to elaborate. He also has been convicted on counts of check forgery and commercial burglary.
Price was shot about a mile from the tennis courts where her younger sisters first rose to prominence in this violence-plagued city southeast of Los Angeles.
The motive and whether she knew her assailant were unclear.
Investigators said Price and a man in the SUV with Price got into some kind of dispute with a group of residents in front of a home on Greenleaf Boulevard, which was known for gangs and drugs.
"At this point we just don't know if this is gang or narcotics," said sheriff's Lt. Daniel Rosenberg, a homicide detective. "I can tell you there are certain indications to suggest this location has involved either gangs or drugs. The house was troublesome."
Sheriee and David Brown, friends of Price, have said she didn't use drugs or associate with gangs.
After the shooting Rolland Wormley, the man in the SUV, drove Price to his relative's house in neighboring Long Beach and called 911. She was taken to a Long Beach hospital, where she died.
The prosecution did not release any information on a possible motive for the killing. Authorities said they had no indication that Price, who lived about 40 miles away in Corona, was involved with drugs or gangs.
Wormley, 28, was arrested for investigation of violating his parole and assault with a deadly weapon using a firearm, sheriff's Deputy Bill Spear said. He did not have details and could not say whether the alleged assault involved Sunday's confrontation.
Wormley has a long criminal history that included convictions for transporting or selling marijuana, vehicle theft, receiving stolen goods and unlawful firearm activity, said Sandi Gibbons, spokeswoman for the county district attorney's office.
Wormley also was expected to be arraigned Tuesday.
Price was divorced and had three children, ages 5, 9 and 11. She is the oldest of five sisters who spent their early years in Compton. She was a registered nurse who owned a beauty salon. She also served as a personal assistant to her famous half sisters, who moved to Florida with their parents when they turned pro as teenagers.
Raymone Bain, publicist for Serena Williams, said the family was in shock.
"They're all together now, leaning on each other, trying to come to terms with this," Bain said. "I know it's going to take them a long time to recover from this."
At an anti-violence rally Monday night, activists and residents raised candles in Price's memory, chanting, "Stop the violence. Increase the peace." Many were saddened that the Williams family couldn't escape the violence.
"Why in this city of all cities? The city they loved. The city that they learned in, that they trained in," asked Patricia Moore, a family friend who has lived here for 30 years. "They've worked so hard to come up. They worked so hard to improve. They represent the highest of the highs for us."
By Jeremiah Marquez