On Wednesday, the city of Chicago revealed the name of the company it used to monitor social media accounts, including those of students in Chicago Public Schools, WBEZ reported.

From 2014 to 2018, the Chicago Police Department paid about $1.5 million to use Dunami, a surveillance software, according to invoices shared with WBEZ. The city didn’t confirm if Dunami was still being used in 2019 or if they’d simply found a new surveillance contractor.

Dunami hasn’t only been used in Chicago. Both the FBI and the Department of Defense have utilized it in the past. According to WBEZ, Dunami identifies influential figures for their clients and maps out human networks, all based on social media.

The city shared Dunami’s name thanks to litigation filed by the American Civil Liberties Union Illinois chapter meant to force the city to release documents in response to a January 2018 Freedom of Information Act (FOIA) request. The ACLU has now officially called for the end of the surveillance program targeting Chicagoans’ social media profiles.

“This invasive program should be suspended immediately until there is time for full, public airing of the reach, power, and use of the tool,” Karen Sheley, Police Practices Project Director of ACLU Illinois, said. “We need time for a new Mayor and City Council to ensure that there is an open process to discuss how this tool works and whether it should be used at all.”

Recently, ProPublica reported that Chicago Public Schools monitored students’ social media, allegedly for signs of violence and gang membership. The district used Dunami util 2017, when officials decided there were methods of social media surveillance that were “more effective and less intrusive”.

Most concerning is that the police department continued using Dunami, even after the school system elected to stop using it. The ACLU also expressed concerns regarding the lack of communication with the public.

“This information should have never been kept secret in the first place,” Sheley said in the ACLU’s release. “The public has a right to know the identity of government contractors in order to assess possible corruption. And the City should not hide such basic information when a tool this invasive is being used.”

According to WBEZ, a city attorney argued in a file that providing more information about the program “would render it ineffective and harm CPD’s ability to use an effective crime fighting tool.”

Dunami isn’t the first program the Chicago Police Department has used to monitor social media. The ACLU found that, from 2014 to 2016, Chicago worked with the social media monitoring vendor Geofeedia — a program that the Boston Police Department also used to monitor hashtags like #BlackLivesMatter, #MuslimLivesMatter, and the use of various, basic Arabic words.  In general, Geofeedia labels activists and unions as “overt threats”.

When it comes to Chicago’s use of Dunami, there are still a lot of unanswered questions, including who else was being monitored and why. Chicago is known for having powerful, grassroots organizing, and the ACLU noted Dunami has been used to spy on protesters in other cities.

As Sheley told WBEZ, “We only have a small snapshot of time that they were doing these searches. We don’t have the full range of it and we don’t have an understanding of everything that the software is capable of.”