Pak previously credited Bottoms’ administration for being more open than that of her predecessor. On Monday, he would not describe how the city had come up short of prosecutors’ expectations.

Pak said “rough spots” are not uncommon for a new administration fielding a complex federal inquiry.

“But we want to continue the dialogue and making sure that we’re getting all the information we need,” Pak said. “We want to get this done as quickly as they do — the new administration does — but we’re not going to take shortcuts. We’re going to do everything that we can. We look forward to talking to them about that.”

Asked again if the city has provided full cooperation, Pak said: “We’re getting cooperation. I’ll leave it at that.”

In a statement, the mayor’s office said “This Administration has and will continue to fully cooperate with the authorities in order to assist bringing the matter to a swift and fair conclusion.”

The federal investigation became public in January 2017 when contractor Elvin R. "E.R." Mitchell Jr. was charged and pleaded guilty to paying more than $1 million in bribes to win city business. Prosecutors later revealed Mitchell started cooperating in July 2015.

Prosecutors have probed sidewalk and emergency snow removal contracts and examined purchasing in several city departments, including the airport and watershed management.

Elvin “E.R.” Mitchell Jr., right, stands with his attorney, Craig Gillen, after Mitchell was sentenced in October 2017 to five years in prison as part of the federal investigation of Atlanta City Hall. HYOSUB SHIN / HSHIN@AJC.COM

Mitchell and four other people so far have pleaded guilty, including two former senior members of the Reed administration. A sixth person, the Rev. Mitzi Bickers, a political consultant who helped Reed win his first run for mayor in 2009 and later served in his administration, has been indicted on charges including bribery and tax evasion.

Bickers has pleaded not guilty and could face trial this year.

Pak would not provide a timeline for when the investigation will be concluded, nor would he say whether other city officials or city vendors might be charged.

“These are serious allegations and whenever we receive a credible lead, we’re going to follow it,” Pak said.

He also renewed his call for witnesses to come forward and cut a deal.

“That clock hasn’t stopped, but the longer you wait the best deals are going to get a little less and less good,” he said.

THE STORY SO FAR

The federal investigation into corruption at Atlanta City Hall has so far netted five guilty pleas, including from two former senior city officials and the CEOs of two city contractors. A sixth person, the Rev. Mitzi Bickers, a well-connected political consultant and former city department head, has been indicted on conspiracy to commit bribery, money laundering and tax charges. She has pleaded not guilty.