State tests determined that fentanyl is the prime suspect in the apparent overdoses that occurred on April 21 and 22.
"Clearly, when you have something like fentanyl, even a search could potentially not discover it, since such minute amounts are all that's needed" for a user to overdose on the highly potent synthetic cousin of heroin, Skinner said.
The Centers for Disease Control and Prevention said fentanyl is up to 100 times more potent than morphine and many times stronger than heroin.
Treating Addiction in Prison
The state senator said she wants prison officials to consider different strategies to curb the demand for drugs behind bars.
"We just do not use the medical treatments for addiction," Skinner said.
She believes drugs like naltrexone and buprenorphine, which are used to treat opioid addiction along with methadone, are underutilized in the prison system, she said.
The medical community supports using the two drugs in the criminal justice system, according to Dan Ciccarone, a professor of family and community medicine at UCSF.
"I think the monthly buprenorphine injection will be a game changer for treatment of opioid use disorder in prison settings," Ciccarone said in an email.
CDCR spokeswoman Vicky Waters said the agency has begun a pilot program using naltrexone for inmates at the California Institution for Women in Corona and the California Institution for Men in Chino.
State prison officials say they treat substance abuse with "detoxification" and "therapeutic rehabilitation."
The CDCR does not use buprenorphine, according to Waters.
What Prisons Do Now to Combat Drugs
Skinner plans to ask officials from the CDCR and the Office of Inspector General (OIG), which oversees the department, to speak to the state Senate's Public Safety Committee in the coming weeks and explain what they've done to cut down on opiates entering the prison system.
The corrections department uses baggage and parcel scanners and metal detectors to prevent drugs from getting inside prison walls, Waters said.
In recent years, the state has spent millions of dollars on drug-sniffing dogs, inmate body scans, visitor searches and restricting drones.
In 2014, the state Legislature approved a two-year, $10.4 million pilot program at 11 prisons to intensify some of those efforts. That funding expired last June.
In the last budget cycle, the CDCR received $6.7 million to expand its drug K-9 program.
Drugs Still Flow In, Deadly Inmate Overdoses Increase
"Methods of introduction are getting more sophisticated," Waters said.
In 2016, 29 inmates died of drug overdoses in California's prisons, according to the CDCR. That year marked the highest rate of drug overdose deaths at state lockups since 2006. Of those cases, 27 were attributed to opioids or methamphetamine.
Between September 2015 and July 2016, seven state inmates died from fentanyl overdoses inside CDCR facilities, according to reports compiled by the OIG.
Donna Strugar-Fritsch, a correctional health consultant with Health Management Associates, said there are several theories that could explain the rise in overdose deaths among California inmates.
It could be that more drugs are entering the prison system, or that the drugs getting into state lockups are stronger, like fentanyl, or that more inmates entering California correctional facilities from county jails may be already addicted, Strugar-Fritsch said.
San Quentin Overdoses
Two inmates at San Quentin State Prison died from "multiple drug intoxication" in 2017 and two died from drug overdoses so far this year, according to Marin County Sheriff's Capt. David Augustus.
Of the four inmate deaths, two involved fentanyl, Augustus said.
This year at least five San Quentin prisoners have experienced suspected opioid overdoses, said Matt Willis, Marin County's public health officer.
"The demand for opioids is present in every community, whether it's San Quentin or in the hills of Tiburon," Willis said in an interview.
"We are seeing, unfortunately, some fentanyl-related overdoses both within the inmate community and in the larger community," Willis said. "That's a trend that's increasing and concerning because fentanyl is a very high-potency opioid and more frequently leads to fatal overdoses."