While CHP officials spent Thursday conducting timing and visual testing in their efforts to determine the cause of a fiery crash that killed 10 people last week on I-5 in Orland, the Glenn County Coroner's office is doing some investigative work of its own.

Identities of six of the nine bodies recovered from last Thursday's crash have already been made public, and Glenn County Coroner Richard Warren is working to make sure the other three are also ID'd.

"Two of them tentatively have come in, we're just working on notification of next of kin on those, and the final one we're still working on trying to get positively identified," Sheriff Larry Jones said. 

Jones, who also works in the coroner's office, says all of the autopsies are complete, but there are still investigations pending. 

"I cannot give you any causes of death at this point, as our forensic pathologist has requested toxicology testing," he said. 

Those tests could offer additional information, including any levels of levels of carbon monoxide in the blood which could help differentiate between possible causes of death.  

They could also determine whether either driver may have had a medical issue. 

CHP Investigators were back at the crash site Thursday, in an effort to piece together what really happened.

Using nearly identical vehicles provided by FedEx and Silverado Stages, CHP officials spent a good part of Thursday afternoon reconstructing the accident.  

They began with a number of visual tests.

"We have a series of cameras set up in the vehicles so that we can identify the visual perspectives the drivers may have had prior to the collision,"  Captain Todd Morrison said. 

Officers then set out to determine how fast each vehicle was driving by re-creating the skidding pattern of the northbound tour bus.  

Those results will be combined with any information that can be retrieved from the badly burned data devices from each vehicle in an effort to get the most accurate results. 

Meanwhile, the 911 calls from the accident have been released. Hear them here.