A Brunswick, Georgia, city commissioner is accused of influencing a witness and obstructing law enforcement in the investigation into the shooting death of a 13-month-old boy, the Glynn County Sheriff's Office said Friday. James Henry Brooks, 59, is being held in jail pending a court appearance, according to the sheriff's office. Police earlier arrested the mother, aunt and sister of one of the two suspects in Antonio Santiago's death on various charges accusing them of hindering the investigation. Authorities say De'Marquise Elkins, 17, and Dominique Lang, 15, shot Antonio in the head after trying to rob the infant's mother as she walked him in a stroller on March 21. Elkins' 19-year-old sister, Sabrina Elkins, was arrested on an evidence tampering charge, the Glynn County Sheriff's Office said. She was named in a grand jury indictment, released Wednesday, accusing her of helping her mother get rid of the gun authorities say was used to kill the child. Authorities did not reveal her alleged role in disposing of the gun, which police found in a pond 2.3 miles from where Antonio died. "She was part of that, and that's the most I can answer of that question right now," Glynn County Police Chief Matt Doering said. The grand jury also indicted Elkins' mother, Karimah Aisha Elkins, 36, and aunt, Katrina Latrelle Elkins, 33, on charges of making false statements or writings, among other things. They had been arrested earlier. None of the women is accused of involvement in the shooting itself. The same grand jury that indicted the women named De'Marquise Elkins and Lang as being involved in the shooting, prosecutors announced Wednesday. Elkins is accused of malice and felony murder, along with other charges. Lang is accused of felony murder. CNN is identifying Lang because he is charged as an adult and media in the community have been naming him since he was arrested. Investigators are looking into the possibility of a gang tie to the shooting, Doering told reporters Thursday. "That's being explored, whether a gang involvement was part of this. And that's all that I can say right now," he said. He declined to say whether more arrests were possible. He said investigators remain in the field, working leads and searching for evidence. The shooting occurred as the baby's mother, Sherry West, was walking her son in a stroller. Two teenagers approached her, and one pointed a gun and demanded money, she said. The boy with the gun said, "'Give me your money or I'm going to kill you and I'm going to shoot your baby and kill your baby,'" West said. She said the boy tried to grab her purse and opened fire when she told him she had no money. He then shot at her -- hitting her in the leg and grazing her head -- and then shot the baby in the face, she said. West tried in vain to resuscitate her son as bystanders called 911 for help. Sabrina Elkins, who is being held without bond, is scheduled to appear before a magistrate at the Glynn County Detention Center on Friday, said April Smith, deputy clerk at the Glynn County Magistrate Court.