Investigators believe Packer, wearing a black motorcycle helmet, entered the couple's beachfront home through an open patio door.
Davina Husted was stabbed first, and as her husband tried to help her, he was attacked. Prosecutors consider this to be a triple killing because Davina Husted was about four months pregnant at the time.
The couple's two children were home at the time, but were not hurt. Their 9-year-old son saw the intruder confront his mother in the kitchen and ran to wake up his 11-year-old sister. They then ran next door to neighbor's house and called 911.
Authorities said the stabbings were some of the most horrific crimes Ventura County have ever seen.
The Ventura County Sheriff's Department believes Packer intended to rob the Husteds. Investigators said they have evidence including phone conversations and text messages. They also recovered some items stolen from the Husteds' home.
DNA evidence collected in a separate case linked Packer to the murders. His DNA was entered into a state database after he was arrested for investigation of robbery at a Santa Barbara gas station in September 2009.
"Numerous search warrants and interviews were conducted, and we believe we have in our possession items used the night of May 20, 2009," said Ventura County Sheriff's Captain Gary Pentis.
Records also show that Packer was charged in Ventura County for misdemeanor battery in November and he was also charged with a misdemeanor hit-and-run in December.
People who grew up with Packer were stunned when they heard about the news of his arrest.
"I'm in complete shock. I would not at all for a second believe that Josh would do this," said Ryan Abundis, Packer's friend.
"I don't think he's capable of it. I mean, we've all made poor decisions, but I don't see him being the one that pushes it beyond that point," said friend James Perry.
Scott Husted, brother of Brock Husted, said the family was grateful for the hard work of detectives. He said there is now some sense of closure but that justice is still years away.
"My mother, last night when I told her, she poured tears that only a mother can shed. She was just grateful that we're at the point that we're at today," said Scott Husted.
Packer was being held in county jail on $2.2 million bail, but that was revoked by a judge Tuesday. He is now being held without bail.
He was charged with three counts of murder with special circumstances that make him eligible for the death penalty if convicted. Other charges include robbery and burglary.