BOSTON - The company that provided the epoxy blamed in the fatal Big Dig tunnel collapse was indicted Wednesday in the death of a motorist crushed by ceiling panels.

Powers Fasteners Inc. was charged with one count of involuntary manslaughter, Attorney General Martha Coakley said. The Brewster, N.Y.-based firm is the only company involved in the construction and design of the tunnel to be indicted by a Suffolk County, Mass., grand jury, Coakley said, noting that the investigation remains open.

A report from the National Transportation Safety Board released last month found the July 10, 2006, collapse could have been avoided if designers and construction crews had considered that the epoxy holding support anchors for the panels could slowly pull away over time.

Milena Del Valle, 39, was killed when 26 tons of concrete panels and hardware crashed from a tunnel ceiling onto her car as she and her husband drove through the westbound Interstate 90 tunnel. Her husband crawled out of the rubble with minor injuries.

Prosecutors said Powers Fasteners knew the type of epoxy it marketed and sold for the nearly $15 billion project was unsuitable for the weight it would have to hold, but never told project managers.

“They failed to make that distinction clear,” said Paul Ware, hired as a special investigator by Coakley.

Jeffrey Powers, president of Powers Fasteners, said the company was unfairly targeted and the wrong product was used in the ceiling, even though his company had filled an order for a different epoxy. The only reason the company was charged was because “we don't have enough money to buy our way out,” Powers said in a statement.

The decision to indict Powers doesn't mean other companies involved in the construction are off the hook, Coakley said. No individuals were indicted, but Coakley did not rule that out in the future.

The maximum penalty for a company charged with manslaughter in Massachusetts is $1,000. Coakley said there may need to be changes in the law, saying the criminal statute may be “wholly inadequate.”

Powers said the company supplied $1,287.60 worth of epoxy for the tunnel. Officials from Coakley's office said the company billed the state more than $500,000 for the whole Big Dig project.

The indictment comes after more than a year of investigations by state and federal agencies, which Coakley stressed are continuing. The charge does not directly affect a separate wrongful death lawsuit that Del Valle's husband and daughter filed against Powers, the Massachusetts Turnpike Authority and eight other companies.

Jeffrey Denner, an attorney for Angel Del Valle, said he believes the grand jury would continue to consider criminal charges against others involved but that it was appropriate to charge Powers.

“They are certainly as culpable as it gets. They are the people who supplied the epoxy,” he said.

In the report released last month, federal investigators spread blame for the collapse among the many corporations, consultants and engineers involved in the Big Dig project, the most expensive highway project in U.S. history. The agency also faulted the Massachusetts Turnpike Authority for failing to conduct a timely tunnel inspection program.

The NTSB singled out Powers for providing “inadequate and misleading” information about its Power-Fast epoxy. Tests had shown the epoxy's “Fast Set” formulation to be “subject to creep under sustained tension loading,” the report said.