Sheriffs departments in the Inland Empire are significantly more likely to transfer prisoners from their jails to U.S. Immigration and Customs Enforcement custody than most California departments, according to a new analysis.
Immigration detainers are requests from ICE asking a law enforcement agency to warn ICE before they release a deportable immigrant and hold them for an extra 48 hours so that immigration agents have time to take them into custody.
In 2025, the Riverside County Sheriff’s Department transferred 158 of the 1,380 people in their jails with a detainer to ICE custody, a rate of 11.4%.
In San Bernardino County, 180 of the 1,674 people with an ICE detainer were transferred, a rate of 10.8%.
Inland Empire sheriff’s departments transferred a higher percentage of prisoners to ICE than the Los Angeles or Orange County sheriff’s departments, which transferred 4.6% and 7.6% of prisoners with immigration detainers on them, respectively.
Across California, in 2025, 2,077 people out of the 24,438 people with immigration detainers were transferred to ICE custody, or 8.49%.
The data was assembled by Keith Maben, a sophomore at Claremont McKenna College and the head of the Immigration Task Force at the Mgrublian Center for Human Rights.
“San Bernardino and Riverside County were on the higher end of enforcement data. So both of them had results where about 10 to 12% of these detainees that came in actually resulted in people (going into) in ICE custody. So, that’s higher than the statewide average, which lies around 8%,” he said.
“Which sounds like not a very large increase. But if you look on the other end of the spectrum, there are a number of counties — for instance, Santa Clara County — which sends less than 1% of those detainees,” said Maben, who’s originally from Santa Clara.
Among the ways the Bay Area’s Santa Clara County is a very different place than the Inland Empire is in its 2024 presidential election results. According to the California Secretary of State’s office, 68% of Santa Clara County voters chose Democratic presidential candidate Kamala Harris. In Riverside County, it was almost a split decision, with 48% of voters going for Harris and 49.3% going for Donald Trump. It was a similar story in San Bernardino County, where 47.5% of voters went for Harris and 49.7% went for Trump.
And you can see that divide in Maben’s results.
The 11 sheriff’s departments that transferred the highest percentage of prisoners with detainers to ICE, according to the Mgrublian Center analysis, were largely conservative-leaning :
- Imperial – 33.7%
- Kings – 29.1%
- Santa Barbara – 24.9%
- Tuolomne – 24.3%
- Del Norte – 22.2%
- Madera – 21.7%
- Lassen – 19%
- San Diego – 15.1%
- San Luis Obispo – 15%
- Fresno – 13.4%
- Ventura – 12.8%
Riverside and San Bernardino county sheriff’s departments ranked 12th and 13th in turnover rates, out of 58 counties.
“More conservative counties tend to elect more conservative sheriffs who tend to enforce California state law in a very different way than more liberal sheriffs do,” he said.
At least, for the most part.
“Interestingly, the county with (one of the) highest turnover rates was Santa Barbara County,” Maben said. In Santa Barbara County, 61.8% of 2024 presidential election voters voted for Kamala Harris.
Maben noted possible problems with some of the data.
He pulled data from the Deportation Data Project website, which in turn assembles its information through public records requests to federal agencies. He was looking at how local sheriff’s departments interpreted 2017’s Senate Bill 54, also known as the California Values Act. The law sets limits on how California law enforcement agencies can work with ICE.
In some cases, sheriff’s departments sign memorandums of understanding clarifying what they will and won’t do with federal immigration authorities, which Maben obtained through California Public Records Act requests.
The Mgrublian Center obtained multiple documents outlining cooperation between Riverside County and federal immigration agencies. They include a 2020 memorandum of understanding with Homeland Security Investigations and a 2024 agreement with the U.S. Border Patrol, both for the purpose of combating drug smuggling operations.
“We found a very strong effect where California sheriffs who tended to cooperate with federal government or have certain memorandums of understanding,” Maben said. “We found they tended to also have enforcement data where more and more of their inmates ended up in federal custody at the end of the day.”
Riverside County’s 2018 ICE Detainer Eligibility Worksheet includes a list of 30 serious or violent felonies that, should a prisoner be convicted of them, would justify deputies notifying ICE prior to the prisoner’s release.
“Effectively telling the the deputies that if you can in any way figure out a way to tie the violation to particular state law, you should do it,” Maben said.
Eddie Torres, policy director of the Inland Coalition for Immigrant Justice, said the Riverside and San Bernardino County sheriff’s department numbers are “alarming, but not surprising.”
He suspects part of the high transfer rates are due to the presence of the Adelanto ICE Processing Center and the Desert View Annex next door in Adelanto.
“When you have a detention center near you, it makes sense you’d have a higher rate of transfers, because it makes logistical sense,” Torres said.
Angel Fajardo, executive director of the Inland Empire Immigrant Youth Collective, agreed.
“Considering the California Values Act passed back in 2018, that is supposed to limit the partnership of local law enforcement with ice and border patrol, it’s ridiculous that this is still an issue,” she wrote in an email.
Inland Empire sheriffs departments “have proven again and again their desire to support detention and anti-immigrant rhetoric,” she wrote.
“We know that the proximity to the largest and deadliest detention center on the West Coast, the Adelanto ICE Processing Center, is also an influencing factor when it comes to our local authorities continuing to ignore the law and transferring our community to this horrible facility,” Fajardo wrote.
The Inland Coalition for Immigrant Justice is spearheading the Shut Down Adelanto Coalition, a group of more than 20 local, state and national organizations attempting to shut down the Adelanto facilities.
“We were really close back in 2023 when the contract was up,” but the federal government ultimately renewed the contract with GEO Group, which operates the two facilities, for another five years, Torres said.
Riverside County turning over a more than average percentage of people with immigration detainers coincides with Chad Bianco’s time as Riverside County Sheriff.
Bianco is now running for governor. His campaign website argues that California needs to “work with the federal government to stop illegal border crossings,” abolish policies like SB 54, and “ensure local law enforcement is free to collaborate with federal partners when dealing with illegal immigrants who commit crimes.”
The Bianco campaign referred all questions to the Riverside County Sheriff’s Department.
“The Riverside Sheriff’s Office complies with the law, and no discretion is exercised,” department spokesperson Lieutenant Deirdre Vickers wrote in an email. “First, the Sheriff’s Office receives a request for transfers from ICE. The Sheriff’s Office then determines the inmates who meet the requirements under SB 54. Of those inmates, ICE determines which inmates are transferred into their custody. The Riverside Sheriff’s Office complies with the transfer request.”
The San Bernardino County Sheriff’s Department disputes the data assembled by Maben. According to the department, 1,423 notifications from ICE were received, not 1,674, and 47 people were transferred to ICE custody, rather than 180.
Maben agrees that the data from the Deportation Data Project is likely imperfect, given that it’s largely reverse-engineered from data obtained through federal Freedom Of Information Act requests, rather than being reported directly by federal authorities.
“I think that it’s important to always take this data with a grain of salt,” Maben said. “It tells us something, but it’s not going to inform the whole story.”
A point ICE agreed with, more or less.
“The Deportation Data Project is an external organization. ICE systems do not support the data provided by this project,” an emailed statement from the agency reads in part. “As a result, ICE cannot verify or confirm the source, accuracy, or completeness of the data the Deportation Data Project uses and how familiar this project is with the intricacies of immigration policy, law, and processes.”
San Bernardino County Sheriff Shannon Dicus also blamed SB 54 for the on-the-street immigration enforcement activities seen since Donald Trump returned to office in 2025.
“From a public safety standpoint, I have been clear that the safest and most controlled environment for the transfer of individuals into federal custody is within a secure jail setting,” Dicus said in a written statement.
“Prior to SB 54, programs like 287(g) allowed for that type of coordination, reducing the need for at-large enforcement actions in our communities,” he continued. “Those in-custody transfers provided a more predictable, secure, and efficient process for law enforcement and reduced risk to the public. Current law prohibits that level of coordination, and as a result, transfers that could occur safely within a custodial setting are now more likely to occur in the field. That shift introduces additional operational risk for federal officers and the public. For that reason, I believe California should reevaluate these restrictions and consider policy changes that allow for safe, in-custody transfers under clearly defined legal standards.”
In Los Angeles County, “a federal judicial warrant signed by a judge must be presented for any inmate to be transferred into ICE custody,” a written statement from the Los Angeles Sheriff’s Department reads in part. “That is consistent with California law and county policy.”
But who ICE does and does not pick up is largely out of local sheriff’s department hands, according to Orange County Sheriff Don Barnes.
“I have nothing to do with how many inmates with detainers ICE picks up,” Barnes posted on Facebook in March. “The only thing I do is make them available for pickup when their commitment is fulfilled. It is ICE’s sole decision on whether they pick them up or not. If they do not pick them up, I am obligated to release them back into the community.”
ICE did not respond to questions about what factors into whether federal immigration agents pick up people from county jails.
The ICIJ’s Torres suspects 2026 will see even more people taken into custody by federal immigration facilities, in part because of the government’s drive to convert warehouses around the country into detention centers.
Locally, immigration agents are conducting fewer arrests in public, switching instead to more “tactical” operations in places like courthouses, according to Torres.
“If they see someone who looks like an immigrant, they arrest first and ask questions later,” he said. “We can’t take our eyes off of what’s going on.”
Maben’s full report for the Mgrublian Center is expected to be published in the next few weeks.