What's a human life worth? Apparently not enough when it came to weighing the possibility that someone might die if a Philadelphia building wasn't demolished properly.

Although they were warned of that danger, none of the people who could have prevented a tragedy acted before the worst thing imaginable occurred. The demolition of a Center City building went ahead and, on June 5, caused a wall to fall on an adjacent Salvation Army thrift store, killing six people and injuring 13.

How do we know there were missed opportunities to prevent deaths and injuries? The parties involved left a trail of e-mails and letters obtained by The Inquirer, which revealed that they failed to act with appropriate urgency even after they were made aware of the potential consequences.

That's not all. The warnings were being made by the owner of the building, STB Investments Corp., which then seemed to ignore its own advice. In a May 22 e-mail lamenting a standstill in negotiations to get the demolition team access to the Salvation Army site, STB property manager Thomas J. Simmonds Jr. said, "This nonsense must end before someone is seriously injured or worse."

That e-mail, which also said the Salvation Army's delays had "created a situation that poses a threat to life and limb," was addressed to Deputy Mayor Alan Greenberger. But Greenberger did not ask the city Department of Licenses and Inspections to take a closer look at the demolition activity. In a statement Tuesday, Greenberger said he received subsequent e-mails saying "the two parties were now working together to resolve the outstanding issues," so he took "no further action."

He should have. The negotiations did not remove the need to look at work said to pose a "threat to life."

Perhaps more information will be revealed at a City Council hearing Thursday. The Mayor's Office initially said it wouldn't participate, but it reversed course on Monday. One can only hope Mayor Nutter's change of heart about that signals additional course corrections on public records pertinent to the fatal collapse. District Attorney Seth Williams' office has said a grand jury investigation shouldn't prevent the city from disclosing information the public has a right to know.

Of particular importance is excavator operator Sean Benschop's successful application to do unrelated city-financed demolition work. Benschop has been charged with manslaughter in the demolition deaths. Nutter should also release the relevant contents of a video made by L&I inspector Ronald Wagenhoffer before he apparently killed himself.

The city can serve its best interests by revealing what responsibility public officials and others had for the poorly planned demolition - and doing whatever is necessary to make sure any mistakes aren't repeated. To do less devalues the six lives lost in the horrific collapse.