An Oakland woman who was allegedly in a romantic relationship with a man accused of killing his wife and mother-in-law in Walnut Creek earlier this month has been arrested and charged with being an accessory after the fact following the deaths, prosecutors announced Tuesday. Yan Wang has been charged with being an accessory after the fact and first-degree residential burglary, both felonies, and misdemeanor destroying evidence. Prosecutors said she allegedly aided Howard Wang with knowledge after the killings and with the intent to help him avoid punishment. Yan Wang was set for arraignment on the charges Tuesday afternoon in Contra Costa County Superior Court in Martinez. “This case serves as a sobering reminder of domestic violence’s far-reaching consequences,” Contra Costa County District Attorney Diana Becton said in a statement.