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Prisons Across the U.S. Are Quietly Building Databases of Incarcerated People’s Voice Prints

The technology also allows authorities to mine call databases and cross-reference the voices of individuals prisoners have spoken with.

An illustration of a prisoner talking on a phone, with a fingerprint in place of his face
Illustration: Alexander Glandien

This story was published in partnership with The Intercept.

Roughly six months ago at New York’s Sing Sing prison, John Dukes says he was brought out with cellmates to meet a corrections counselor. He recalls her giving him a paper with some phrases, and offering him a strange choice: He could go up to the phone and utter the phrases that an automated voice would ask him to read, or he could choose not to and lose his phone access altogether.

Dukes did not know why he was being asked to make this decision, but he felt troubled as he heard other men ahead of him speaking into the phone and repeating certain phrases from the sheets the counselors had given them.

I was contemplating, ‘Should I do it? I don’t want my voice to be on this machine,’” he recalls. “But I still had to contact my family, even though I only had a few months left.”

So, when it was his turn, he walked up to the phone, picked up the receiver, and followed a series of automated instructions. “It said, ‘Say this phrase, blah, blah, blah,’ and if you didn’t say it clearly, they would say, ‘Say this phrase again,’ like ‘Cat’ or ‘I’m a citizen of the United States of America.’” Dukes said he repeated such phrases for a minute or two. The voice then told him the process was complete.

“Here’s another part of myself that I had to give away again in this prison system,” he remembers thinking as he walked back to the cell.

Dukes, who was released in October, says he was never told about what that procedure was meant to do. But contracting documents for New York’s new prison phone system, obtained by The Appeal in partnership with The Intercept, and follow-up interviews with prison authorities, indicate that Dukes was right to be suspicious: His audio sample was being “enrolled” into a new voice surveillance system.

In New York and other states across the country, authorities are acquiring technology to extract and digitize the voices of incarcerated people into unique biometric signatures, known as voice prints. Prison authorities have quietly enrolled hundreds of thousands of incarcerated people’s voice prints into large-scale biometric databases. Computer algorithms then draw on these databases to identify the voices taking part in a call, and to search for other calls where the voices of interest are detected. Some programs, like New York’s, even analyze the voices of call recipients outside prisons to track which outsiders speak to multiple prisoners regularly.

Corrections officials representing the states of Texas, Florida, and Arkansas, along with Arizona’s Yavapai and Pinal counties; Alachua County, Florida; and Travis County, Texas, also confirmed that they are actively using voice recognition technology today. And a review of contracting documents identified other jurisdictions that have acquired similar voice print capture capabilities: Connecticut and Georgia state corrections officials have signed contracts for the technology (Connecticut did not respond to repeated interview requests; Georgia declined to answer questions on the matter).

Civil liberties advocates argue that the biometric buildup has been neither transparent nor consensual.

Authorities and prison technology companies say this mass biometric surveillance supports prison security and fraud prevention efforts. But civil liberties advocates argue that the biometric buildup has been neither transparent nor consensual. Some jurisdictions, for example, limit incarcerated people’s phone access if they refuse to enroll in the voice recognition system, while others enroll incarcerated people without their knowledge. Once the data exists, they note, it could potentially be used by other agencies, without any say from the public.

It’s particularly alarming, they add, that the technology’s use in prisons can ensnare people beyond their walls. “Why am I giving up my rights because I’m receiving a call from somebody who has been convicted of a crime?” asks Jerome Greco, a digital forensics attorney at New York’s Legal Aid Society. Greco argues that the mining of outside parties’ voice prints should require a warrant. “If you have a family member convicted of a crime, yet you haven’t been, why are you now having your information being used for government investigations?

Illustration: Alexander Glandien

The spread of voice recognition technology

Voice print technology works by dissecting physical features that distinguish individuals’ voices, such as their pitch. With this data, the program’s algorithm generates a computer model of their vocal signatures, known as “voice prints,” which can be stored in a database for comparisons with utterances recorded in the future.

In recent years, voice recognition technology has come to be associated with consumer offerings, like Amazon’s Alexa and Apple’s Siri, but the technology was originally developed for military and intelligence applications. Over a decade ago, as The Intercept reported, U.S. intelligence agencies were using voice recognition programs to identify the voices of top Al Qaeda officials in their online audio postings.

Similarly, the algorithms and structure behind the prison telecommunications firm Securus Technologies’ particular voice software, known as Investigator Pro, were developed in part through a $50 million grant from the Department of Defense. The software was licensed to JLG Technologies, a company that Securus acquired in 2014. According to Securus’s 2017 proposal for New York, the technology was developed because “DOD needed to identify terrorist calls out of the millions of calls made to and from the United States every day.”

But it wasn’t long before major prison technology firms, such as Securus and Global Tel Link, began marketing the technology to U.S. jurisdictions that were seeking to extract and store voice prints associated with incarcerated people in their systems. “IPRO [Investigator Pro] has a 10-year track record of providing pinpoint voice accuracy capability country-wide in 243 states, county, and local correctional agencies,” notes Securus in the Pinal County contract.

The enrollment of incarcerated people’s voice prints allows corrections authorities to biometrically identify all prisoners’ voices on prison calls, and find past prison calls where the same voice prints are detected. Such systems can also automatically flag “suspicious” calls, enabling investigators to review discrepancies between the incarcerated person’s ID for the call and the voice print detected. Securus did not respond to a request for comment on how it defined “suspicious.” The company’s Investigator Pro also provides a voice probability score, rating the likelihood that an incarcerated person’s voice was heard on a call.

Michael Lynch, an intelligence coordinator for the Alachua County Jail in northern Florida, confirmed that his county recently agreed to purchase Securus’s voice recognition program. Lynch said that the voice prints produced by the program will be permanently archived at Securus’s facility in Texas. He said the jail hopes the technology will address the problem of incarcerated people using each others’ personal identification numbers, or PINs. “The problem is inmates that are committing other criminal acts or contacting victims or witnesses and using other inmates’ PIN to do that,” he said in a phone call. “Voice [biometrics] will tell us who’s making the calls.”

Image of Securus’s Investigator Pro VoiceSearch tool from a 2017 approved contract proposal with Pinal County, Arizona

Securus’s voice recognition program can also identify the voices of people outside prisons, both former prisoners and those who have never been incarcerated but communicate with people inside.

New York and Texas state corrections officials confirmed that their agencies retain the voice prints of formerly incarcerated people, like Dukes, allowing them to identify them by name if currently incarcerated people call them in the future.  

And New York and Pinal County, Arizona, confirmed that their voice recognition programs can identify the voices of outside callers.

New York’s contract proposal with Securus states that outsiders’ voice samples can be used to “search for all other calls” in their recorded call database to find where those voices occur. In an email, New York prison officials confirmed that this program will give investigators the ability to extract a voice print from an outside caller and use it to “identify that a call recipient has participated in multiple phone calls.” They added that the program will not have names associated with outsiders’ voice prints.

In a statement, Pinal County Sheriff’s Office spokesperson Navideh Forghani also confirmed this outsider voice tracking capability, noting that while their software does not identify non-incarcerated people by name, it can track “suspicious activities” such as “multiple inmates speaking to one person on the outside on a reoccurring basis.”

With this technology, a press release for Investigator Pro notes, an investigator can now answer questions like, “What other inmates are talking to this particular called party?” and “Are any of my current inmates talking to this released inmate?”

Prisoners’ rights advocates worry that outsider voice surveillance technology could also be used to coordinate crackdowns against prison organizing campaigns.

“Using this technology to trace the voices of outside callers and flag those who speak with more than one person in a system, staff can use calls with outside organizers to quickly identify the incarcerated activist they support,” said Bianca Tylek, director of the Corrections Accountability Project, which works to curb the influence of commercial interests in the criminal justice system. Tylek noted that during the 2018 national prison strike, corrections staff routinely retaliated against incarcerated activists by using tactics like solitary confinement, job termination, and facility reassignment.

Illustration: Alexander Glandien

The pressure to participate

Advocates assert that corrections agencies have been building up large-scale voice print databases with limited input from the public, or from incarcerated people and their families. While some state corrections agencies have put out public notices to families about payment options for new phone systems, they seldom mention the voice print databases, which are rarely discussed outside of industry conferences and internal talks with contractors.

Every time there’s a new contract, there’s new surveillance, but they don’t say anything,” said Tylek. “I’ve never seen authorities post a public notice about new surveillance updates or tell families.”

Keeping their plans opaque has allowed authorities to quietly pressure incarcerated people into giving up their biometric data—or to enroll them without their knowledge. According to Securus’s 2019 Investigator Pro contract with Alachua County, Florida (which includes Gainesville), “Inmates will participate in a covert voice print enrollment process.”

In Texas, state prisoners must enroll in the voice recognition program if they want to make calls. According to Jeremy Desel, a spokesperson for the Texas Department of Criminal Justice, Investigator Pro’s voice enrollment process is “the lock and key” to the Texas state prison phone system. Likewise, in Pinal County, Arizona, phone access is severely limited for prisoners who decline to enroll in the voice recognition program. “If inmates choose not to participate, they can still utilize the phone system but only to make phone calls to their attorneys,” said Forghani, the county sheriff’s office spokesperson.

A lot of guys don’t know technology. They’ve been in there so long, they’ve never heard of Google.

Martin Garcia prisoner at Sing Sing

In some cases, prisoners participate without even knowing, said Martin Garcia, a 33-year-old who is incarcerated at Sing Sing in New York.

“A lot of guys don’t know technology,” he said. “They’ve been in there so long, they’ve never heard of Google.” The voice enrollment procedure, he continued, is seen as “just another thing they follow to talk to their family.”

Garcia was upset to hear that Securus’s voice tracking capabilities, as described in its approved contract with the New York State Department of Corrections and Community Supervision, could mine prison call databases to identify which other prisoners outside callers had contacted. “Are they criminals just because they’re talking to someone incarcerated?” he said. “To me, you’re criminalizing relationships. Some people may be hesitant to interact with me if they could be put in a database.”

After being briefed by The Appeal and The Intercept about the program, New York State Assembly member David Weprin publicly called on the state Department of Corrections to give incarcerated people more choice regarding the voice recognition program. At a Tuesday hearing, Weprin, chairperson of the Assembly’s Committee on Correction, asked the Department of Corrections’ acting commissioner, Anthony J. Annucci, to add a provision that allows incarcerated people with legitimate concerns about voice surveillance to “not be denied phone privileges.” Annucci did not immediately agree to the request, instead pointing out that people have the option to make unmonitored calls to their attorneys.

In a statement to The Appeal and The Intercept, Weprin said he is “concerned with the deployment and use of voice recognition software” in New York state prisons, and will be working with his colleagues to further investigate the technology.

Building the databases

The rapid, secretive growth of voice print databases is “probably not a legal issue, not because it shouldn’t be, but because it’s something laws haven’t entertained yet,” noted Clare Garvie, a senior associate at Georgetown Law’s Center on Privacy & Technology. “It’s not surprising that we’re seeing this around prisons, just because it can be collected easily,” she continued, referring to biometric voice data. “We’re building these databases from the ground up.”

The scale of prisons’ emerging voice biometric databases has not been comprehensively documented nationwide, but, at minimum, they already hold more than 200,000 incarcerated people’s voice prints.

New York’s Department of Corrections, which incarcerates just under 50,000 people, confirmed that approximately 92 percent of its population had been enrolled in the voice recognition system. State corrections authorities for Florida, Texas, and Arkansas, which hold about 260,000 prisoners combined, also confirmed that they are using Investigator Pro’s voice recognition technology. Connecticut and Georgia’s state corrections systems, which incarcerate roughly 13,000 and roughly 52,000 people, have also purchased Securus’s voice print technology.

The databases of recorded calls from which prison authorities could search for outsiders’ voice samples could also potentially include millions of recorded calls for state and countywide systems. According to the design requirements New York’s Department of Corrections gave to Securus, for example, the company must be able to record every call, archive all call recordings for a year, and maintain any calls flagged for investigative purposes “indefinitely” through the life of the contract, which ends in 2021. (In the documents, Securus estimated that 7 percent of prison calls made per year would total 1.5 million calls, suggesting that the call database could retain over 20 million calls.)

Once the data exists, and it becomes an accepted part of what’s happening, it’s very hard to protect it or limit its use in the future.

Jerome Greco Legal Aid Society

Greco of the Legal Aid Society says he understands the value of such monitoring capabilities, pointing out that incarcerated people do sometimes have to deal with other prisoners taking their PINs or threatening their families for money. But the extension of this technology into the monitoring of people outside prisons, and the lack of transparency and regulation of these new databases concerns him. If voice prints were shared with police, for example, they could try to compare them with voices caught on a wiretap, he notes, despite scientists’ skepticism about the reliability of voice print matches for criminal prosecutions. New York State’s Department of Corrections declined to answer questions regarding whether it would share the data with other agencies.

Either way, Greco said, there’s cause for concern. “Once the data exists, and it becomes an accepted part of what’s happening, it’s very hard to protect it or limit its use in the future,” he said.

That has implications far beyond prisons, argues Garcia, the man incarcerated at Sing Sing. “First you use this on the people marginalized in society, criminalizing the families of those incarcerated,” he said. “But, especially in Trump’s America, the sky is the limit with this.”

Contact reporter George Joseph on the secure phone app Signal at 929-282-2471 or by email at with another protonmail account. Contact Debbie Nathan at