(CNN)As the search continued Tuesday for three siblings and questions mounted over how the rest of their family ended up dead at the bottom of a California cliff, investigators hope a laptop and iPad yield clues, an affidavit shows.
Police search for travel records, suicide notes in family's SUV cliff plunge
Police seized the devices from the Woodland, Washington, home of Jennifer and Sarah Hart, on Thursday, according to court documents related to the search warrant.
In the affidavit requesting the search warrant, a Clark County, Washington, sheriff's deputy says he is seeking evidence that will shed light on what happened to the family. That evidence could include travel itineraries, bank records, phone records, credit card receipts, hotel receipts or "handwritten or typed journals or notes related to travel, care for the children and or suicide note/s."
It adds that the California Highway Patrol's investigators believe "a felony has been committed."
The bodies of the mothers, both 38, were discovered inside their overturned SUV near a remote stretch of Highway 1 in Northern California on March 26. Jennifer Hart was in the driver's seat, according to the search warrant affidavit.
Emergency responders found the bodies of three of their six adopted children -- Markis, 19, and Jeremiah and Abigail, both 14 -- outside the car, which landed upside down on the rocky shoreline below the cliff.
Evidence from the scene and data retrieved from the car has led investigators to believe Jennifer Hart may have intentionally drove the SUV off the cliff.
Their other children -- Hannah, 16, Devonte, 15, and Sierra, 12 -- are missing. Nobody reported seeing the crash.
Though a police news release says the California Highway Patrol and Mendocino County Sheriff's Office are continuing an "active search" for the missing children, the search warrant affidavit says they, too, may have been in the SUV.
The kids "have not been located and it is feared that they may have also been involved in the collision and presumed deceased," the affidavit says.