When Big Dig tunnel ceiling fell, mere accident or crime?

The collapse of ceiling panels in one of Boston's Big Dig tunnels this week caused a fatality. So was it just an accident or a crime?

So far, state investigators are treating it as a crime. In an unusual move, Massachusetts Attorney General Tom Reilly says he is pursuing a criminal investigation instead of a civil suit, which is normally employed after construction accidents. The action is unlikely to send contractors or government officials to prison, legal experts say, but the action does give prosecutors additional legal tools to look for wrongdoing.

Such tools may be crucial as investigators focus on just how much contractors and managers knew about problems with suspect bolt fixtures prior to Monday's failure.

Transportation officials have linked those bolt fixtures to the collapse of concrete ceiling panels, which killed a Boston woman. Now, Mr. Reilly is charging that contractors knew as early as 1999 that there was a problem with those bolts because five of them failed during testing.

"It was not only identified, but there was a plan to address that problem," he said. "What we're trying to determine right now is: Was that plan implemented?"

Those revelations, together with the discovery of some 60 problem areas throughout the damaged tunnel, may help investigators with a criminal case based on prior knowledge and criminal negligence.

The picture is complicated by election-year politics. Reilly is running for governor this November and some commentators have suggested that his moves in the investigation are, in part, politically motivated. Several legal experts disagree, pointing out that by launching a criminal investigation, Reilly will be able to subpoena a grand jury and compel the contractors who built the tunnel to produce otherwise private documents.

"If he's approached this investigation with 'I want to charge someone with a crime,' that's unfortunate," says Edward Ryan, former president of the Massachusetts Bar Association. "If he's approached the investigation with 'What happened?' that's the proper attitude."

Reilly told reporters on Tuesday that the investigation could lead to a charge of negligent homicide, for which the government would bear the burden of proving, beyond a reasonable doubt, that the tunnel's contractor acted with "wanton and reckless conduct."

That doesn't mean showing that workers or contractors acted with malicious or criminal intent. But it would require proof that a defendant made flawed decisions with almost deliberate indifference – despite knowledge of the deadly risks involved.

"That's a very high standard that has to be met," says Arthur Leavens, law professor at the Western New England College School of Law. "That's much higher than garden-variety negligence that would support tort recovery or civil recovery."

There's a fine line, say attorneys, between the kinds of mistakes that end up in a lawsuit and the kind that put people in jail.

"It's going to turn on the facts and the nuances of what people knew and didn't know," says Mr. Ryan. "If the engineer was aware of instances of ceiling collapse for identically configured ceilings, but recommended this configuration for the project anyway, now you've got the kind of knowledge that I'm talking about."

Indictments and convictions are not outside the realm of possibility.

"It's relatively unusual to bring a criminal charge based on a construction accident," says Professor Leavens. "But it's not unprecedented."

The most famous precedent for a manslaughter conviction also took place in downtown Boston.

Massachusetts authorities charged Barnett Welansky with manslaughter after a large fire killed some 492 customers in his Coconut Grove nightclub in 1942. Prosecutors in the case, which eventually wound its way to the US Supreme Court, were able to prove that the absentee Welansky had willfully disregarded the danger to his patrons when he let his staff lock the doors, fill the club to twice its legal occupancy, and festoon the ceilings with flammable décor.

But in another case similar to Monday's Big Dig accident, prosecutors failed to convict three contract workers and a Cambridge construction company after a bridge in Worcester, Mass., collapsed in 1968, killing three people.

• Wire services were used in this report.