Hercules police detectives traveled to a King County, Wash., Jail, jail, to interview 24-year-old Darnell Washington and his wife, Tania Washington, 25, about the death of Susie Ko.
They determined the couple were suspects in Ko's stabbing death, Hercules police spokeswoman Connie Van Putten said in a statement Friday.
The Washingtons were arrested Wednesday in Ko's stolen vehicle after a brief pursuit in SeaTac, a suburb of Seattle.
Ko, 55, was found dead on the floor of her home by neighbors on Oct. 5. An autopsy report said she died of stab wounds and blunt force trauma to the head, Van Putten said.
On Aug. 27, Darnell Washington was being held at the Glen Helen Rehabilitation Center in Devore awaiting trial for a 2011 robbery when he escaped with help from his wife and another inmate, authorities said.
Washington simply scaled the fence, San Bernardino County sheriff's officials said. Since the escape, sheriff's officials said they would be reviewing security at the jail, used mostly to house low-risk inmates. The jail's capacity is 1,024 inmates.
On Sept. 2, a Los Angeles County sheriff's deputy spotted a suspicious vehicle parked outside a 7-Eleven in South El Monte. Believing it may have recently been carjacked, the deputy called for assistance.
Before back-up could arrive, the Washingtons spotted the deputy and fired a shotgun at him, wounding the deputy in the leg, authorities said.
The deputy suffered minor injuries.
The Washingtons fled and within an hour, carjacked another vehicle from South Gate, authorities said.
The killing of Ko was the first in Hercules since 2010, and the city has seen only seen five homicides in the past 12 years, Van Putten said.
Charges of murder and auto theft will be presented to the Contra Costa District Attorney's Office late next week, Van Putten said.
Booking records in King County, where the couple were being held, indicate they have been booked on suspicion of murder, assault, weapons charges, vehicle theft and attempting to elude police.
The Associated Press contributed to this report.