Two former senior Justice Department officials are calling on their colleagues to investigate a secretive warehouse used for interrogations by Chicago police and likened to a CIA “black site” facility.

Sam Bagenstos, who during Barack Obama’s first term was the Justice Department’s No 2 civil rights official, said that the Guardian’s exposé of the Homan Square police warehouse raised concerns about “a possible pattern or practice of violations of the fourth and fifth amendments” that warranted an inquiry.

William Yeomans, who worked in the civil rights division from 1981 to 2005, and served as its acting attorney, said the allegations about off-the-books interrogations and barred access to legal counsel reported by the Guardian merited a preliminary investigation to confirm them, a first step toward a full civil rights investigation.

“I would certainly call on them to take a look at it, yes,” Yeomans said.

A Guardian investigation details a secret facility where Americans were unable to be contacted by their legal counsel while locked inside and repeatedly denied access to basic constitutional rights.

At Homan Square, a nondescript warehouse on the city’s west side, police arrest or detain people for hours without booking or otherwise posting public notifications of their whereabouts, preventing their relatives knowing where they are.

Numerous lawyers reported difficulties getting basic information about their clients from Homan Square, with three saying they had personally been turned away by police from entering the building even as their clients were inside. Police denied access to a Guardian reporter who showed up at the facility to seek answers.

“It certainly raises the very serious question about whether there is a pattern of practice of constitutional violations, of excessive force, denial of right to counsel, coercive interrogations,” said Bagenstos, now a law professor at the University of Michigan.

“This is definitely the kind of practice that you would expect the Justice Department to look into.”

The Justice Department did not return a request for comment by press time.

In operation since the late 1990s, Homan Square is used by special police units, including those investigating gangs and narcotics, that do not operate out of specific police districts. It also is home to an evidence and recovered-property locker. While marked and unmarked police cars line the parking lots and a barrier blocks traffic out front, prominent signage does not indicate that it is an official police facility.

Were he still at the Justice Department, Bagenstos said, “this would be the kind of matter that I would want at least a preliminary investigation of, to see whether it warranted a full-scale investigation.”

“The allegations are certainly disturbing. People are going in there and disappearing? Their attorneys are not allowed to have contact with them? That’s very disturbing,” said Yeomans, now a fellow at American University’s Washington College of Law.

After the Guardian published its story on Tuesday, the Chicago police emailed a statement that did not respond to any of the Guardian’s specific questions. The police department cited the presence of undercover units as necessitating secrecy around Homan Square.

“CPD [the Chicago police department] abides by all laws, rules and guidelines pertaining to any interviews of suspects or witnesses, at Homan Square or any other CPD facility. If lawyers have a client detained at Homan Square, just like any other facility, they are allowed to speak to and visit them,” the statement read.

Several lawyers interviewed by the Guardian said they were prevented from seeing their clients at Homan Square.

“There are always records of anyone who is arrested by CPD, and this is not any different at Homan Square,” the statement continued.

Several lawyers interviewed by the Guardian, however, said that once their clients entered Homan Square, no public records were generated that provided indications of someone’s whereabouts.

Bagenstos said it was difficult to disentangle the “dark history” of interrogation by Chicago and other law enforcement agencies from a post-9/11 militarization of domestic policework to trace the origins of the disquieting Homan Square allegations.

“It’s certainly not the kind of story that you expect to read as a present-day piece of journalism as opposed to a piece of history,” Bagenstos said.