The eight-year-old was found dead inside a Merced home a little more than a week ago.
Officials say the Hayward Police Department in Alameda County reached out to Merced police concerned over Sophia's whereabouts.
Officers searched a home in Merced and found Sophia's body.
RELATED: Child found dead inside Merced home is missing 8-year-old Sophia Mason, authorities say
Investigators say she had been missing for a month.
Since then, her mother, Samantha Johnson, has been arrested for her murder.
Saturday night, family members gathered outside of Hayward City Hall to celebrate Sophia's life and call for systemic change on her behalf.
"But if any of you know anything, we can't save Sophia, but we can do this one thing for her. We can find the person who did this," said Melissa Harris, Sophia's aunt.
VIDEO: Family of 8-year-old girl found dead in Merced home speaks out
Family of 8-year-old girl found dead in Merced home speaks out
Sophia's mother remains in the Merced County Jail. She's being held without bail on a murder charge.
Police are still searching for Dhante Jackson. He was Johnson's boyfriend. Officials say he's also wanted for Sophia's murder.
Anyone with information is asked to call the Merced Police Department.