Supervisor David Canepa authored the ordinance on the grounds it will bring more equality to asylum seekers and prevent collusion from Immigration and Customs Enforcement.
But critics argue that argument is getting more controversial as newly-released data suggests the legislation may overlook public safety.
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"Do you know the recidivism rate of a convicted criminal seeking asylum in San Mateo County?" ABC7's Stephanie Sierra asked.
"I don't know, I don't know," Canepa told the I-Team last week.
There isn't a comprehensive analysis of immigrants who repeatedly commit crimes, but the I-Team recently obtained data through public records that revealed a pattern from 2018-2021.
The San Mateo County Sheriff's Office stopped cooperating with ICE in November 2021, but before that law enforcement documented the number of ICE transfers.
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According to the sheriff's office, there were at least 35 cases where immigrants convicted of serious felonies in the county had a long history of prior arrests.
That list includes people convicted of multiple lewd acts with a child under 14 years old, rape, child abuse, DUI with injury, grand theft, transporting 30 pounds of meth with intent to sell, elder theft, assault, robbery and arson.
The I-Team found a pattern of recidivism among this group.
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One immigrant charged with a drug felony was booked in county jail 20 different times. Another person charged with vehicle theft was booked in county jail 17 different times. And four others charged with assault with a deadly weapon and DUI with injury were booked 11 different times.
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Supervisor Ray Mueller was the only one to vote against the ordinance during an April 11 board meeting. He proposed adding three amendments that would exempt asylum seekers convicted of murder, rape and child molestation --- but the amendments failed.
"I will not be voting to support this measure," Mueller told the I-Team. "Let's just say the scenario is if someone returns to the community who is a dangerous and violent felon who has been deported or has just returned to the community, the only way our sheriff will be able to work with ICE to remove that individual will be to sue the board of supervisors."
The I-Team spoke with Canepa last week discussing concerns over recidivism rates.
Sierra: "Why didn't you support the three exemptions for those convicted of murder, rape, and child molestation?"
Sup. Canepa: "When it comes to those types of crimes you're exactly right... we're not going to cooperate with ICE. Why should there be double punishment?
Sierra: "But the question, supervisor, was why didn't you support those three exemptions?"
Sup. Canepa: "The answer to that... we took it on its totality, Stephanie. We heard from families... There are people that have served their time. They should be released."
Sierra: "The DOJ has done a study that found child molesters with previous sexual offenses have the highest recidivism rate. Does that change your answer?"
Sup. Canepa: "No. Look Stephanie, that's not going to change my mind."
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Data obtained by the I-Team also shows a pattern among some immigrants in San Mateo County. Of the cases we analyzed, two stood out. The immigrants were convicted of sexually abusing children. One was arrested and booked in county jail a total of five times for other crimes. While the other person was arrested and booked a total of 14 times for other crimes.
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The I-Team requested a follow-up interview with Sup. Canepa, but we were told he was unavailable.
The legislation is supported by more than a dozen local organizations but also has opposition from well-known immigration rights advocates, like Joaquin Jimenez.
"It's difficult to actually advocate for their rights, when they continually break the law," said Jimenez. "Especially after the shooting of seven farm workers in our community. How about them? How about their rights and their families?"
In January, immigrant Chunli Zhao was charged with seven counts of murder after allegedly opening fire on his co-workers at two mushroom farms in Half Moon Bay.
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Jimenez is worried immigrants released from state prison and deported will come back to retaliate.
"There's been cases where people actually get deported and they come back... They come back to the same community," said Jimenez. "It does happen."
Supervisor Canepa says if there's someone undocumented suspected of murder or rape, the county will cooperate with a federal criminal investigation. But, Sup. Mueller says it's not that simple.
"The sheriff is not working with immigration officials as a policy, but she has the discretion in extreme and violent cases to deviate from that policy," said Mueller. "Should the ordinance pass tomorrow, Sheriff Corpus loses that ability and discretion."
Take a look at more stories by the ABC7 News I-Team.