A source emailed two reporters at the Phoenix New Times last month, telling them that Immigration and Customs Enforcement agents were regularly raiding Motel 6 locations in the city and detaining guests.

“We were like, ‘This is totally crazy—if it’s happening,’” says Antonia Noori Farzan, one of the alt-weekly’s reporters, in an interview with CJR.

It was happening. As New Times reported on Wednesday, two Motel 6 hotels systematically shared their guest lists with ICE. The other reporter on the story, Joseph Flaherty, says many of the arrested guests have been deported, and other cases still are pending.

ICYMI: Toronto Star wine column leaves bad taste

In Phoenix, ICE raids are common. To prove the two motels were tipping off the authorities, Farzan and Flaherty combed through a year’s worth of online court records. After weeding out ICE referrals stemming from unrelated arrests, they found the same addresses popped up over and over again.

Farzan and Flaherty, who worked on the story for exactly a month and have teamed on stories in the past, also called immigration attorneys, many of whom recalled clients who had been picked up at a Motel 6. It was clear there was a pattern. But they still didn’t know what led to the arrests.

Sign up for weekly emails from the United States Project

“We were trying to figure out who was contacting who in this scenario,” says Flaherty. “Was it the clerks who were proactively sending the list to ICE? Was it immigration officers that were proactively calling the motels saying, ‘We’d like the list’?”

Farzan and Flaherty started showing up at the motels in question, trying to talk to people who worked there. Neither of them ever checked in themselves, though Farzan considered it. “I definitely spent some late nights hanging out in the parking lot, being mistaken for a prostitute repeatedly,” she says.

TRENDING: 10 podcasts to help you keep up with the news cycle

They suspected that one or two staff members might be responsible, or that guests checking in with Mexican IDs were being individually referred.

Farzan asked a clerk outright whether they were reporting certain guests to immigration authorities. “I was told, ‘Oh no, we give everyone’s information to ICE,’” says Farzan. “Did I hear that correctly, could you say that again?” she recalls. “It was definitely a big shock.”

Flaherty called and emailed corporate management at the Motel 6 chain multiple times for comment throughout the reporting process. They heard nothing back until after the story was published, at which point the company said the guest referral policy had been “implemented at the local level without the knowledge of senior management” and had already been “discontinued.”

After New Times Story, Motel 6 Says It Will Stop Sharing Guest Lists With ICEhttps://t.co/MgUKucKBEN — PhoenixNewTimes (@phoenixnewtimes) September 14, 2017

Flaherty says he expected the investigation to turn heads in the Phoenix area, but its ripple has been felt across the country at a moment of acute anxiety, in many quarters, about the Trump administration’s immigration policies. On Friday morning, Democratic US congressman Ruben Gallego, who represents the district where the hotels are located, fired off a letter to ICE demanding clarification on how ICE was tipped off.

ICE was randomly accosting Latino guests at @motel6 hotels in AZ. We need to know who signed off on it: https://t.co/yO2Cw34hqn pic.twitter.com/6bFVIsQ6e9 — Ruben Gallego (@RepRubenGallego) September 15, 2017

Flaherty was back on the beat on Friday, covering a protest outside one of the Motel 6 locations in Phoenix.

Phoenix New Times is known for its aggressive and ambitious journalism; in August it gained national attention with a long series of tweets drawing attention to its past reporting on Sheriff Joe Arpaio, the radical immigration hardliner recently pardoned by President Trump.

Farzan and Flaherty see their reporting as an advertisement for alt-weeklies, which have been struggling to stay afloat. “It shows people should support their local alt-weeklies,” says Farzan. “Someone working on a national scale may not have the time and opportunity to go through court records. Not that we really had time, but we made it work.”

Someone working on a national scale may not have the time and opportunity to go through court records. Not that we really had time, but we made it work.”

Farzan and Flaherty don’t intend to stop reporting anytime soon. “We still have a lot of questions about how [the hotel started telling ICE about its guests]. Who initiated the practice of giving a guest list to immigration officers? We just don’t know at this point,” says Flaherty.

They hope that local papers in other parts of the country will conduct similar investigations in their areas.

“I’ve already been talking to a bunch of other local journalists because we are really curious about whether this has happened in other places. Motel 6 says this is something that only happened on the local level, but obviously we’re skeptical of that,” says Farzan. “If anyone wants to try this, get in touch with me.”

TRENDING: Reporter asks for 20 years of lottery winner data. Then, he notices something unusual.

Has America ever needed a media watchdog more than now? Help us by joining CJR today

Jon Allsop is a freelance journalist. He writes CJR’s newsletter The Media Today. Find him on Twitter @Jon_Allsop.