McNulty said the city would not name the agency because "the law department and OMI do not release the names of witnesses or interviews done in investigations," and because the city considers the agency to be "like a witness."
That stance worries the ACLU's Walczak, who argues the public can't possibly assess the validity of an investigation conducted anonymously. "If it's the Acme Plumbing Company, it's probably not worth a lot," he says.
"I'm not aware of any legal reason why they can't release additional information," Walczak adds. "It's not like you could compromise some ongoing part of the investigation."
Other police departments are less reluctant to release details of internal investigations — including that of Madison, Wis., where Cameron McLay, the city's new chief, served as a police captain.
Within three hours of a call from City Paper, Madison police made available an internal investigator and captain who supervises the division in charge of releasing public information.
"During an investigation we don't typically release anything," says Madison police Capt. Sue Williams, who cautions that differences in local and state law make it impossible to compare policies exactly. But "once the investigation is closed — especially if it's a high-interest story — we try to release some information so our public knows what's going on. It's constantly a balancing test."
Madison's police department is more likely to disclose information related to investigations that sustain charges of wrongdoing, as opposed to investigations that result in exonerations, Williams says. But after a 2012 incident where an officer fatally shot an unarmed robbery suspect, the department decided to release video of a witness interview conducted during the investigation to convince the public the department made the right call.
"The decision has to be as transparent as possible," Williams says, "so we can foster [...] trust in our community."
In Pittsburgh, though, the police union's Campbell doesn't think more disclosure is likely.
"It's either confidential or not confidential and I think [...] for these investigations to be effective in the long run, it can't be a public thing," Campbell says. "You can't cut the baby in half."