The 57-year-old was found dead on her bedroom floor with blood coming from her mouth and ears.
Click in the Eyewitness News story window above to watch Eileen Frere's report from the scene.
Her body was discovered by her sister, who stopped by to pick up their 87-year-old father for an Easter Sunday get-together.
She called 911.
Authorities then found her 51-year-old brother Daniel dead in his bedroom in the back of the house, with dark shoe polish smeared on his face.
"Daniel Savage actually drank that black shoe polish that accounts for the polish around his mouth and face," said Jim Amormino of the Orange County Sheriff's Department.
Authorities do not know if the shoe polish caused his death, and autopsies came back inconclusive pending further toxicology tests.
Police believe the brother and sister may have been dead for two days, which means their father was living with the bodies in the Cowan Heights home they shared, unaware of what had happened.
"Some days are better than others. He recognizes some people some days, and some days not. It's just one of those things that it's a shame it happens to someone as kind and great as he was," said Eben Howard, a family friend.
"The father was a colonel in the U.S. Marine Corps. His name is Richard Doc Savage. He flew by the call sign "Doc" in several combat missions in Vietnam," Amormino said.
Authorities said Jacquelyn and Daniel cared for their father.
Neither the father nor his son Daniel have criminal records.
Jacqueline, however, pled guilty to forgery of prescriptions and second degree burglary in 2000, according to court records.
Authorities are unsure if the deaths are murder-suicide or death by natural causes.
Whatever happened inside the house is, so far, baffling to seasoned investigators and disturbing to residents in the otherwise quiet neighborhood.
"It's shocking when anything like this happens in Orange County," said Shaelan Bowers, a neighbor.
Anyone with information should call the Orange County Sheriff's Department at (714) 647-7000.