The timeline for building a new downtown Minneapolis stadium for the Minnesota Vikings has always been tight.

Last week, it got a whole lot tighter.

When the Minnesota Sports Facilities Authority, the public body overseeing construction of the nearly $1 billion venue, ordered a deeper background check into team owner Zygi Wilf and his family, it pushed back important decisions on lease and development agreements that could affect plans to break ground on the project later this fall.

The additional scrutiny is in response to a New Jersey judge's ruling this month that Zygi Wilf and his brother Mark were guilty of fraud, breach of contract and violations of the state's civil racketeering statute in connection with a real estate partnership. In announcing the decision, Superior Court Judge Deanne Wilson delivered sharp words for Zygi Wilf, saying his testimony exhibited "bad faith and evil motive." That criticism prompted Gov. Mark Dayton, the lead stadium promoter, to urge the authority to conduct a more thorough review of the Wilfs and the team's commitments to the $975 million stadium project to ensure that they are "truthful and accurate."

"We're still on track and still on schedule," said Michele Kelm-Helgen, the authority chairwoman. "But this certainly has complicated things."

Stadium builders have long said that a fall 2013 construction start is a must if the building is to open in time for the 2016 NFL season. Tentative plans call for a late October or early November groundbreaking.

Any delay that results in a postponed opening could cost "millions" to both sides, said Lester Bagley, the Vikings' vice president of public affairs.

John Wood, senior vice president of Mortenson Construction, the stadium builder, said Friday that his team is "moving forward with the expectation that the additional due diligence work will be completed to the authority's satisfaction.

"We'll just keep doing what we're doing until our client tells us otherwise. And so far, nobody has suggested anything other than that we're still on schedule."

Regardless of the date for the ceremonial groundbreaking, Wood said "major construction work" won't begin until mid-November.

'Need to know'

Just how quickly builders can move will depend on the outcome of the deeper background check and whether the sum of the damages the Wilfs must pay after losing the civil case will affect their ability to finance the project.

Kelm-Helgen said the additional background investigative work by a securities attorney and an international forensic accounting firm hired by the authority last week could be completed "in weeks," and possibly before mid-September, when the judge in the civil case, who plans to retire later in the month, is expected to announce her decision on damages.

Assuming the additional scrutiny of the Wilfs' financial and legal backgrounds turns up nothing more, "we definitely can proceed with everything else," Kelm-Helgen said. "We don't anticipate that we will find anything. We just need to know the money will be there and that our partners are still on firm financial ground and that there are not other lawsuits out there that could potentially inhibit their ability to do business."

The Vikings are responsible for $477 million of the stadium construction cost with the state of Minnesota and city of Minneapolis picking up the rest. The team's financing will come from a $200 million NFL loan and revenue generated from stadium naming rights, sponsorships and licensing fees.

The NFL, the Wilfs and the Vikings have repeatedly assured the authority in recent days that their commitments to the project won't be affected by the litigation.

Bagley said four "major banks" are working with the team to line up project financing and that they plan to talk with attorneys and financial experts conducting the background checks.

"Those conversations will make it clear that this lawsuit, regardless of the outcome, will have no impact on team's ability and owner's ability to finance this project," he said.

Until the background checks are completed, however, the team and authority can't finalize stadium lease and development agreements, which will dictate everything from who controls construction to how much season-ticket holders will pay in license fees to reserve the best seats. The authority planned to vote on those agreements at its Aug. 23 meeting, but those negotiations have been pushed back. Both must be finalized and approved before the state sells taxpayer-backed bonds to pay its share of the project.

The city of Minneapolis also has yet to sign off on the stadium's schematic design. A City Council vote on that question is scheduled for Aug. 30.

"We have built in some cushion over time and there's not much cushion left," Bagley said. "So we've got to buckle down and get this done.

"So far, so good," he added, speaking of the project design and construction timeline. "But there are benchmarks that we have to meet."

One of the first comes in November, when Mortenson orders the steel for the massive truss that will support the stadium roof.

Wood said the order is "critical to the schedule" because the truss must be "produced, shipped and fabricated" by August 2014 to coincide with the start of steel erection on the project.

Kelm-Helgen said the authority and Mortenson have had many discussions about the initial steel order, and that everything is on schedule.

But, Wood said, "If we are unable for whatever reason to order that steel in early November, then it starts to potentially impact the completion date."

Richard Meryhew • 612-673-4425