“Failure to preserve this information could have serious consequences,” Wistow wrote.

Wistow and attorney Jonathan Savage are in the process of investigating who might be at fault for the bridge’s failure, declaring earlier this month it was “open season” on any potential defendants.

The letter also invites each company to inspect the bridge — under supervision ― before it is demolished, taking with it any evidence that the companies might want to use in their defense.

“While that investigation proceeds, efforts are already underway to stabilize the bridge (so that it does not catastrophically collapse) and, eventually, to demolish and replace it,” Wistow wrote. “Those efforts cannot be delayed. … We are inviting you to inspect the bridge now, prior to its demolition.”

The companies have until May 11 to contact the firm to schedule an inspection.

Reached by phone, Wistow said the 12 companies have all either done construction, design or inspection work on the bridge. He said he could not say if these are the only possible defendants in the case, or if there could be others.

“We do not yet know who any defendants will be,” Wistow wrote in the letter. “Therefore, you should not interpret your receipt of this letter to mean that you will be named as a defendant if suit is brought. You may consider it prudent to notify your insurance carrier of this letter.”

The companies that received the letter are AECOM Technical Services, Steere Engineering, PRIME AE Group, Cardi Corporation, Barletta Heavy Division, Aetna Bridge Company, Vanasse Hangen Brustlin, Commonwealth Engineers & Consultants, TranSystems Corporation, Collins Engineers, Michael Baker International, Jacobs Engineering Group.

Six of the firms are based in Rhode Island or Massachusetts.

It’s not immediately clear how long it would take for the companies to inspect the bridge if all of them choose to take the state up on the offer. But Wistow told the Globe the process of allowing potential defendants to inspect it would not delay the demolition.

“We’re not going to sit here and keep it in a pristine condition for you to come and inspect it,” Wistow said.

The Rhode Island Department of Transportation last week put out a call for companies to bid to demolish the bridge, a process that is slated to start in July and end in March 2025.

The DOT on Tuesday separately issued a request for bids to build the new bridge, which is slated to open sometime in 2026.

The westbound span of the Washington Bridge was abruptly shut down on Dec. 11 after an engineer doing work on the bridge flagged a “critical failure.”

The bridge, which used to carry 90,000 cars a day over the Seekonk River to Providence, was initially expected to be repaired and reopened within three months. But new problems were uncovered during inspections, prompting McKee to announce in March that the state will demolish and reconstruct the bridge.

The eastbound span, which is a separate and newer bridge, remains open and is now being used for both eastbound and westbound traffic on I-195.

McKee has promised a “day of reckoning” for anyone involved in the bridge’s failure. The state was in the process of rehabilitating the structure when the failure was discovered.

The lawsuit is focused on contractors that might result in money recouped for the state, but Wistow said if the investigation finds that any Department of Transportation employees were at fault, that would be reported.

“There’d be very little point of suing DOT,” Wistow said. “But if we uncover something about DOT that was inappropriate, we’re going to report it to the proper authorities.”

See more coverage of the Washington Bridge closure in R.I.

Steph Machado can be reached at steph.machado@globe.com. Follow her @StephMachado. Brian Amaral can be reached at brian.amaral@globe.com. Follow him @bamaral44.