Detectives don't know who murdered 58-year-old Barbara Latiolais in her home at 2431 San Carlos Avenue in the wee hours of last Thursday.
They can't even be sure whether she died as a result of the brutal assault she sustained or the arson that was apparently set to obscure the scene.
What detectives do know is that the victim's long-term partner, retired San Francisco firefighter Michael Rice, 60, "is in no way, shape or form a suspect," as Alameda County Sheriff's Department spokesman Sgt. J.D. Nelson said at a news conference Tuesday afternoon.
That is when authorities issued a sketch of a short, dark-complected male in his late teens who was seen in the vicinity of the crime. This unknown suspect is thought to have abandoned a 2006 black Volvo SUV -- stolen from the victim's home -- at the end of Brookdale Boulevard a few hours after the attack
Investigators say they are determined to hunt down the killer or killers who perpetrated a crime so brutal that it shocked even their hardened sensibilities.
"A crime like this touches the family, it touches the community, it touches the investigators," said Detective Lieutenant Colby Staysa, who said the killing "was one of the most violent that we've seen."
Now authorities vow to leave no stone unturned in their hunt for the suspect or suspects who perpetrated these acts.
They think the suspect has some connection to Castro Valley and that some one may have seen him, and are asking anyone with information to call 510-667-3636.