Less than six months have passed since Sonoma County supervisors scrapped plans to buy an office building near Charles M. Schulz-Sonoma County Airport amid accusations of impropriety and overpayment. And now the deal has resurfaced under the allure of “new information” shared behind closed doors.

If the county is seriously reconsidering a deal, it needs to explain to the public what has changed and why the cost is worth it.

The county needs better space for public employees. Several buildings on its 1950s-era Santa Rosa administrative campus do not meet modern seismic standards. They have faulty sewage systems and leaky roofs. They show their age. County government cannot operate indefinitely in buildings that are crumbling around employees and members of the public who have business with the county.

A handful of departments are already in offices at the airport area building, a high-end facility at 400 Aviation Blvd. The county’s lease expires in 2031 and is expensive. Rather than pay rent, county officials reasoned, it might be better to buy the building outright. Last year, supervisors considered paying $56 million for it.

The conversation soon got messy. It turned out that $56 million was $10 million more than the highest appraised value. That additional money would cover technology, energy efficiency, furniture and other features in the building, but it still struck a lot of people as a hefty premium for used chairs and network routers.

Then a union representing county employees revealed that Supervisor David Rabbitt had received a $1,000 campaign contribution from the agent for the real estate broker handling the sale for the building’s owner, American AgCredit. The union, SEIU, filed a complaint with the state Fair Political Practices Commission. Rabbitt returned the money, and there is no reason to believe he was swayed by the donation, but it created an appearance of a conflict of interest. The FPPC is still investigating.

With those issues, the county walked away.

Now county officials are reconsidering in light of that “new information” presented to supervisors in a recent closed session. They cited confidentiality provisions for real estate transactions to justify the secrecy.

There is a time for government to hold its cards close to its chest during negotiations, but this is not it.

What has changed? Is the price lower? Are there better terms? The public should not have to wait for a finalized sale to find out.

Under California law, appraisals and other details will become public records after a sale is complete. But officials have the discretion to waive that secrecy.

The county could and should open up to the public. Explain what makes this worth consideration. Give residents an opportunity to assess whether it is a good deal and to share their opinions.

A $56 million purchase would impact county finances and operations for decades. The decision about it should not occur out of public sight. Supervisors say they will not move forward if the deal is not good enough. If they get to the point that they believe it is good enough, they should not fear showing their work to taxpayers.

Supervisors need a four-member supermajority to approve the purchase. That threshold reflects the state’s recognition that public real estate deals deserve broad consensus.

Earning that consensus requires making a public case, not simply emerging from a closed session with a deal in hand.

Sonoma County needs new office space, and it might well need 400 Aviation Blvd. Before the ink dries on a deal, the public needs to know that its tax dollars are being spent responsibly.