Coke, 50, disappeared on August 4, when her 15-year-old daughter said she left their home to meet with someone about the family's missing dog.
Police believe that Coke was last seen with Randy Alana, a 56-year-old sex offender she briefly dated two decades ago. Alana has previously been convicted of rape and kidnapping.
Though officials would confirm that Coke had been murdered, they wouldn't provide any more details about her manner of death.
Alana, a person of interest in the case, was taken into police custody August 6 on a parole violation.
In a statement, the Coke family said they were "devastated" to hear the news.
"Those of us who were privileged to know Sandra will remember her as an unusually kind, generous and big-hearted person," the statement read. "She passionately devoted her professional life to helping the poor and those who endured difficult childhoods."
We want to express our deepest thanks to the hundreds of caring people in local, state and federal law enforcement, current and former colleagues, friends, and members of the public and the media -- who labored day and night to assist with the search for Sandra. Your care and expressions of concern have been humbling.
Coke worked as an investigator for the federal public defender's office in Sacramento. Many of her co-workers helped authorities look for her.