Dang Tran was booked into the Santa Rita jail Tuesday. The 21-year-old is accused of driving too fast and under the influence of marijuana when he caused this crash on I-880 near Stevenson Boulevard.
But for a second straight day, Alameda County prosecutors delayed and ultimately canceled his arraignment.
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Prosecutors then revealed to ABC7 News that they have been unable to charge Tran with the evidence they have so far and are asking the California Highway Patrol to continue their investigation.
"The investigation in this matter is ongoing and the DA's Office requires additional information as well as investigation prior to making a charging decision," a spokesperson wrote in a statement to ABC 7 News.
Prosecutors have not said what information they still require from the CHP investigation.
A family consisting of a man, woman, and their six daughters were in this SUV that Tran allegedly crashed into.
Noelle Johnson, 39, 14-year-old Christy Limas, and her 9-year-old sister Brooke were killed.
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The family was headed home to Manteca after celebrating another daughter's 4th birthday in the Bay Area.
Family friends of the victims were outraged.
"We know he's responsible for their deaths. Why haven't they been able to charge him?" Amy Mooney wrote to ABC7 News.
She was worried about what could happen after Tran was released.
"They need to revoke his driver's license. They need to revoke his passport so he can't get away."
Prosecutors appear to be keeping open the option of filing charges in the future when they think the evidence supports it.
Click here for more on how the community is reacting to this tragic event.