The Department of Homeland Security is expanding its capacity to scan irises as part of its mass deportation efforts, a move that has raised concerns among privacy experts that the agency, flush with an influx of funding, is gathering biometric data from people it detains.

The agency awarded a $25 million no-bid contract last week to BI2 Technologies, a company that specializes in iris scanning. The new contract is more than five times the amount of the company's last DHS contract, awarded last fall. NPR reached out to BI2 multiple times regarding its work with ICE, but did not hear back.

As part of its proposal to the company, DHS requested more than 1,500 iris scanners, as well as access to the company's mobile app, including a database where iris scans are stored. Irises contain intricate patterns that are unique to each person, similar to a fingerprint.

DHS declined an interview, but told NPR in a statement that ICE officers use iris recognition technology "to assist in accurately identifying individuals encountered during immigration enforcement and removal operations, including confirming identities and backgrounds of individuals who may be subject to enforcement actions."

That may include people like Norelly Mejías Cáceres. One night last fall, she was with her husband and first grade son in her Chicago apartment when a Black Hawk helicopter filled with federal immigration officers descended on the building.

"We were in our room. We were sleeping. When they knocked on the door, they were pointing guns at us and they ordered us to leave," Mejías told NPR, speaking through an interpreter provided by the University of Chicago Immigrants' Rights Clinic, which is representing Mejías in a complaint against the federal government.

Mejías fainted during the raid. When she came to, officers pointed a smartphone at her face to take her photo, she says. She had been crying and her eyes were swollen.

"They asked me to open my eyes wide for the photo, so I did. I opened my eyes wide for the camera," she said.

The officers were then able to identify her. Mejías, who had a pending asylum case, was detained and eventually deported. She is now living in Venezuela with her family.

Nicole Hallett, a law professor at the University of Chicago and director of the Immigrants' Rights Clinic, believes the officers wanted more than just an image of Mejías' face: She thinks they wanted a photo of her irises.

"There were other people who were arrested during this raid who reported having a photo taken of them and then having details about them known to the officers. Norelly is the one that we were most certain was an iris scan because of the detail about how she needed to open her eyes," Hallett said.

Sheriffs have used the technology for decades. A video on BI2's YouTube channel says it was created 20 years ago. During the first Trump administration, the company donated iris scanners to sheriffs in the Southwestern Border Sheriffs' Coalition, a group of sheriffs serving counties along the U.S.-Mexico border.

Justin Smith, executive director of the National Sheriffs Association, says he used BI2 iris scanners in his jail for booking when he was the sheriff in Larimer County, Colo. He described it as a camera device mounted on a pole that detainees looked into when they arrived at the jail. The captured image then went into a database.

Smith says his deputies also used BI2's smartphone app in the field to identify people. He says it was particularly useful when officers were looking for someone specific, but who did not have identification. The only option in that scenario to identify the person, he says, would be to take them into custody to do fingerprints, which takes time. He says he can see how identifying someone quickly could be helpful in targeted immigration enforcement.

"They're trying to quickly identify within a large group, 'who do we have here?'" Smith said. " It allows them to clear up people: 'Hey, we know who this person is. This is not the person you're looking for.'"

But, Smith says, any technology that can access someone's private information has the potential to be abused, and the question of how law enforcement should use a certain tool depends on acknowledging that.

"I would say it's a balance test. It's not a black and white, always this, never that," Smith says. "It's a matter of: How is it used?"

In the case of the Chicago apartment raid for instance, Hallett says, "The only way they were able to identify people was to illegally arrest them and then use this technology in order to identify them."

"This is troubling because we really want law enforcement to be targeting particular people about which it has particular information," Hallett added. "And here the government knew nothing before they pointed the device at our client and were able to call up her information from the databases."

Hallett is not the only person who doesn't trust ICE to use its technology appropriately against protesters and undocumented immigrants, in particular.

"This agency has already proven themselves to be a very rogue agency," says Cooper Quintin, a senior staff technologist with the Electronic Frontier Foundation, a nonprofit that advocates for digital privacy. "Could ICE start doing iris scannings of everybody they detain and then add that to their database and use that for further surveillance? Yeah, absolutely."

There is some precedent for that concern. NPR has documented multiple cases of federal immigration officers taking another type of biometric data, DNA samples, from people they arrested, including legal observers and protesters who said they were peacefully exercising their first amendment rights.

Marianna Poyares, a researcher at the Center on Privacy and Technology at Georgetown Law, says there are cases where biometrics are used simply for identification, such as when someone passes through airport security.

But, she says, the implications change when sensitive information is stored alongside other sensitive information. She says there are a lot of unanswered questions.

"What else is being collected?" Poyares said. "Is there any kind of oversight as to who is overseeing these databases? What kind of data is being combined and aggregated and for what use?"

In its statement, DHS told NPR that it is using "every tool available" in its efforts to find, detain and deport undocumented immigrants. And as its budget surged in the last year, the agency has collected a lot of tools to do so – facial recognition technology, license plate readers and location trackers, among others.