Thursday, officials will -- finally -- break ground on the long-awaited renovation of the Nassau Coliseum.

But even as the work begins, the persistent and complex questions about this project are unending. Who exactly is the county doing business with? And as the players change, what will it mean for the Coliseum and its surrounding property?

Two years ago, when Nassau County officials signed a 25-year lease with an entity called Nassau Events Center to renovate and operate the Coliseum, developer Bruce Ratner led the effort. A chart in the lease, which runs more than 100 pages and contains maps, photos and more, showed Forest City Enterprises, Ratner's company, as the central company involved, and Forest City was listed as the "completion guarantor," responsible for making sure the project got done.

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The chart showed that beyond Forest City, Nassau Events Center included Blumenfeld Development Group, LiveNation, Legends, Guggenheim, and Onexim Sports and Entertainment.

But last week, that structure changed. Now, 85 percent of Nassau Events Center is owned by Onexim, a company headed by Brooklyn Nets owner Mikhail Prokhorov. A high-profile Russian oligarch, Prokhorov is worth about $10 billion and maintains a powerful political and economic presence in Russia, and a portfolio ranging from nanotechnology to mining.

What's more, Forest City officials confirmed that key partners Guggenheim, Legends and Blumenfeld are no longer a part of Nassau Events Center. The lease permits all of the changes, but they leave the future cloudy. The county should consider tightening the permissions in future deals.

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For now, county and Forest City officials say nothing's changed. Forest City is still the "managing partner." The $261 million project is being overseen by Ratner and Brett Yormark, the chief executive of Barclays Center in Brooklyn, which Ratner developed and where Prokhorov is a minority stakeholder. The lease is still in force; the renovation, operation and revenue plans are the same, the county says.

That may be true.

But there's been nothing but silence from new lead tenant Prokhorov, who has never met with owner Nassau County's representatives, County Executive Edward Mangano or the Nassau legislature. Indeed, the county knows very little about the very hands-on man who now holds the purse-strings on its most significant economic development project. With $90 million coming from EB-5 money provided by Chinese investors in exchange for visas, there are plenty of unknowns involving foreign investment. And no one but Prokhorov can say what he wants, how he's going to proceed and on what timeline.

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Prokhorov should come to Mineola, meet with Mangano and answer questions at a public hearing held by the legislature. The county needs to know who he is and what he plans. Perhaps the promises will become reality. But too many unanswered questions remain.