Prosecutors say that Sandra Jessee, 58, and Thomas Aehlert, 39, had Jack Jessee, 58, killed a decade ago because they thought insurance wouldn't fully cover the medical bills and they didn't want to spend retirement savings on his cancer treatment.
The mother and son pleaded not guilty in 2007 to murder for financial gain and felony conspiracy. If convicted, they face life in prison.
Aehlert is accused of hiring a friend, Brett Schrauben, 37, for $50,000 to kill his stepfather. Prosecutors say Schrauben and another man stabbed Jack Jessee at his Placentia home in August 1998.
Sandra Jessee moved to Arizona after she collected $650,000 in life insurance, her husband's retirement savings and proceeds from the sale of their home, prosecutors said.
Aehlert later met Schrauben several times to make remaining payments for the murder, prosecutors said.
In 2005, new information surfaced that linked the suspects to the crime, said district attorney spokeswoman Farrah Emami. She said she could not elaborate.
Schrauben pleaded guilty to voluntary manslaughter last year and is scheduled to be sentenced in July.
Emami said the fourth suspect has not been charged due to lack of evidence.