Packer, 20, is accused of murdering Brock Husted and his pregnant wife Davina in their beachfront home in May 2009.
The couple was stabbed to death, while their two young children were still in the house. The Husted's 9-year-old son and 11-year-old daughter escaped without physical harm. They ran to a neighbor's house for help.
Packer was arrested in April and has been ordered held without bail. Police said DNA played a role in Parker's arrest.
Chief Deputy District Attorney Michael Frawley says prosecutors have not decided whether to seek the death penalty if Packer is convicted.
The Associated Press contributed to this report.