Missing Oakland Investigator's Friend Fears 'Something Has Happened'

PHOTO: Sandra CokePlayOakland Police
WATCH Federal Investigator Disappears After Mysterious Call

The disappearance of a Bay Area federal criminal investigator, who vanished following a tip on her stolen dog, has sparked a police search. Her worried friend believes that "something has happened" to her.

Sandra Coke, 50, an Ivy League graduate and investigator for the public defender's office, was last seen at her home on Sunday by her 15-year-old daughter. A spokesperson for the family said she left the house to follow up on that lead related to her missing dog.

"There's no question something had happened. There's no way she would have ever left her daughter there alone," Wendy Springer, Sandra's best friend, told ABC News.

For weeks, Coke had been looking for her beloved dog, Ginny, who disappeared after someone broke into her home in May. Coke offered a $1,000 reward on missing posters. Tips were called in, but they all were dead ends.

This past weekend Coke discovered a new lead in finding Ginny.

"She told her daughter that someone called about the dog," her sister Tanya Coke said.

Coke's family said she left the house to meet the caller, hoping to be gone for a half hour, but never returned. Coke's daughter then tracked her mom's work and personal iPhones using a GPS application. Both had apparently been dumped: one on a Richmond, Calif., Highway, the other near Oakland.

"The phones were still working the next morning, sending a signal," Tanya Coke said.

Police found Coke's car two miles from her home.

"It's absolutely heart wrenching," Tanya Coke said, "Every parent, every sibling's nightmare. It's especially upsetting that she might be in danger and that there is foul play here."

On Wednesday, investigators took bags of evidence from Coke's home, including her laptop computers, hoping to find clues.

Police won't say if they believe Coke's work helping win release for inmates on death row, or the search for her missing dog, have anything to do with her disappearance.

"She was very attached to the dog and very concerned about trying to get her back," said Joe Schlesinger, a friend for over 20 years. Schlesinger and Coke work with death-row inmates in the office of Federal Public Defenders.

"We work on cases where there are all kinds of tragedies and it isn't the most popular work, but we have no reason to believe her disappearance has anything to do with the crimes she was investigating," said Schlesinger. "She was a committed, stable person that wouldn't just wander off."

Coke's family and friends are vowing to keep searching until they find her.

"She's a very special person," Springer said. "Unusually kind and generous and big hearted."

Sandra Coke is described as 5-foot-6 and 150 pounds, with a medium complexion, brown hair and brown eyes. She was wearing a black-and-white shirt and dark jeans when she disappeared. Anyone with information on her whereabouts is asked to call Oakland police.

ABC News' Josh Haskell contributed to this report.