JUST WHEN IT looked as if Governor Paul Cellucci was going to skip off to Canada without having to answer any questions regarding what he knew about Big Dig overruns and when he knew it, Attorney General Tom Reilly’s office announced that it will indeed be investigating the Central Artery/Tunnel Project budget scandal. On Tuesday, the AG’s office issued subpoenas to the governor’s office, the offices of the Massachusetts Highway Department (which oversees the Big Dig), and a host of other government agencies.

Since last month’s release of Inspector General Robert Cerasoli’s 78-page report documenting evidence that Big Dig and federal transportation officials have known since 1994 that the massive public-works project would cost taxpayers $14 billion, there’s been nary a peep about the governor’s role. The Boston Globe’s Eileen McNamara wrote a strong column headlined start talking, governor on March 25 and the Boston Herald editorialized on the issue March 22, but politicians have been all but silent. And that’s because most of them put political self-interest ahead of public-policy considerations.

Republicans don’t want to delve into this mess because it happened on the GOP’s watch. And Democrats would just as soon see Cellucci move to Ottawa, leaving a politically weakened Lieutenant Governor Jane Swift in charge of the state — an easy target in the 2002 governor’s race. Of course, there’s another reason no pols have questioned the mounting budget overruns over the years — and why, even now, Congress is all but ignoring Cerasoli’s disturbing report: the Big Dig is the single largest example of bipartisan pork ever produced by Congress. Tip O’Neill, then Speaker of the House, pushed the project through Congress in the early 1980s. Bechtel/Parsons Brinckerhoff — a consulting agency that’s been a home to any number of conservatives, including such Reagan-administration officials as former defense secretary Caspar Weinberger and secretary of state George Schultz — won the bid to manage the project. In other words, Republican money interests and Democratic labor constituencies both benefit. Who in Congress would want to mess with that?

All of which makes for an ugly political spectacle.

After all, Cerasoli’s report clearly demonstrates that in 1994, when the Big Dig was publicly estimated to cost $8 billion, B/PB’s president and one of the company’s senior partners personally met with then-governor William Weld and his advisers to tell them that they believed the project would eventually run to $14 billion. At the time, Cellucci was head of the governor’s Big Dig Oversight Task Force. Cerasoli’s report concludes that Cellucci “likely knew” of the projected overruns. When that’s put in context with an intriguing remark Weld made to Boston magazine last May, it certainly sounds as if Cellucci knew. “When Cellucci and I were out on the hustings in central and western Massachusetts, we didn’t want to tell the town fathers and mothers that we were going to take all their statewide road and bridge money and use it to pay for the Central Artery Project,” Weld said.

If Cellucci did, indeed, know about the overruns, then why did he allow the low-budget fiction to continue when he became governor? And why didn’t he disclose this information to Wall Street bond analysts on December 3, 1999, when he met with them to discuss the state’s bond rating? Perhaps most disturbing is that an outside counsel to the Big Dig faxed a memo to Big Dig officials the night before this meeting took place, outlining a $1.4 billion overrun. As Cerasoli’s report notes, “This message included a hand-written warning: ‘these are hard numbers — not worse case’” figures.

Seven days later, a bond sale raising money for the Big Dig took place. Bond analysts were not told of the overruns. When this information became public in early 2000, the Securities and Exchange Commission launched an investigation. Intriguingly, State Treasurer Shannon O’Brien sensed that something was wrong with the Big Digfinances. So she conducted a due-diligence review of Big Dig finances for the December 1999 bond offering. It was her investigation that forced the disclosure of the overrun in January 2000. How could Cellucci, who’s occupied a seat of power at the State House in one form or another since 1990, not have been aware of the same information O’Brien was able to ferret out after just two years in office?

And then there’s the matter of a “confidential” timetable labeled “Budget Exposures and Offsets” that appears to plot political events, such as the presidential election and the 2002 gubernatorial election, against Big Dig highlights and projected overruns. One explanation given for the document — which was dated May 1999, eight months before the overrun was publicly announced — is that Big Dig officials were worried about disclosing the overrun in an election year, when the possibility of raising more money for the project would have negative political repercussions. Of course, bureaucrats don’t necessarily need to worry about these considerations — but politicians do.

Maybe it’s true that Cellucci, like Sergeant Schultz, knew absolutely nothing. Then, of course, all that great stuff we heard throughout the early 1990s about how Cellucci was a co-governor with Weld was nothing but a lie. But that’s unlikely. As Cerasoli’s report concludes: “Based on these records and the disclosure of these facts in 1994 to the former Governor and his chief advisors, the Office concludes that the current Governor and his appointees have not disclosed the real Big Dig budget story to federal investigators, Congress, the State Treasurer, and the State Legislature.”

While Congress seems more than willing to give Cellucci a pass on these questions, the state attorney general isn’t so compliant. Thanks to Reilly, maybe we’ll finally get the truth.

What do you think? Send an e-mail to letters[a]phx.com.