Police said Elizabeth Benson, 84, was repeatedly stabbed during a violent home-invasion robbery in June of 2009.
Her alleged killer, Bryan Roy Thomas, was arrested more than a year later, but the case was not closed.
"We've kept it as part of the ongoing investigation," said Rialto police Lt. Joe Cirilo. "This is not yet over just because we had one suspect."
Frank Ronald White is now wanted in connection to Benson's murder.
Police believe he, along with Thomas, broke into Benson's home to rob her.
Despite her age and 4-foot-11 stature, Benson put up a fight.
"I know that these cowards had laid in wait to attack my little mom," said Benson's daughter, Cynthia Benson-Davis. "They tortured her until she died."
Benson-Davis only recently learned police were searching for a second suspect.
"I am glad I didn't know ahead of time because I would have been afraid," she said. "I was afraid until the first guy got arrested. Now I am in fear there is a second person out there."
Detectives said White was a person of interest from the beginning, but they didn't have enough evidence until now to pursue charges.
An arrest warrant for $1 million was issued for White, who is also a wanted parolee.
"Mr. White played a role in this," Cirilo said. "I can't be more specific in that other than he played a major role in committing this homicide."