Individuals in Connecticut’s political circles have speculated for more than a year about how and why the federal government began investigating an alleged conspiracy to bribe former House Speaker Chris Donovan.

U.S. Attorney Christopher Mattei put that speculation to rest Monday when he opened the trial of Donovan’s former campaign finance director, Robert Braddock Jr.

According to Mattei, Patrick Castagna, a former employee of Tracey’s Smoke Shop in Norwalk, told FBI agents in New York that he suspected individuals were trying to bribe Connecticut officials in an effort to kill legislation that would have raised taxes on roll-your-own tobacco shops.

Castagna became a cooperating witness in the federal investigation.

Braddock was the only one of eight men charged last summer on corruption charges who pleaded not guilty.

He was charged with three counts of conspiring to hide the source of $27,500 in campaign donations to Donovan on behalf of a group of smoke shop owners looking to defeat legislation.

Braddock’s trial started today in U.S. District Court in New Haven.