Joanna "Asha" Veil was last seen alive walking home from her job at the Ben Lomond market in 2006, when she was seven months pregnant.
Police have arrested Michael McClish, a manager at that market. Prosecutors plan to charge him with two counts of murder.
"In our lengthy investigation we have found that Michael McClish had both a motive and an opportunity to commit these murders. Asha and McClish had both a professional and a personal relationship."
McClish is already serving a life sentence for rape, in an unrelated case. Police say the victim's estranged husband was the father of her unborn child, not the suspect.