Authorities are still investigating the causes of three women's deaths last week, which they suspect may be drug-related.
The women - 27, 32 and 59 years old - died within about five days of each other.
Toxicology tests are being conducted and the process is being expedited, but it could still take a few weeks for any conclusions, sheriff's Commander Bill Steven said.
The reports should shed light on whether the three deaths can be linked to a controlled substance, though authorities are still conducting an overall investigation into the deaths, Steven said.
If a controlled substance is to blame, things to consider would be whether the drugs were contaminated or purer than the users expected, Steven said.
Last week authorities speculated that a bad supply of methamphetamine or heroin could be involved.
"There's also the possibility that none of them are linked together and it's just a coincidence," said Steven.
An investigation into the source of the drugs is being hampered by people unwilling to speak to authorities, Steven said.
"It's a difficult investigation when you're dealing with people who don't want to talk despite the fact it could cost more lives," said Steven.
Autopsies completed on the three women came up inconclusive regarding a direct cause of the deaths, said sheriff's Commander Tim Athey.
The Sheriff's Office is also awaiting a response from Sutter Coast Hospital as to whether any patients have been treated recently who showed similar signs of trouble after drug use, he said.
"We need to know whether these are isolated incidents or if there are folks that have actually survived this," said Athey.
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