A conspiracy theory has been circulating for weeks in the Democratic primary for Pennsylvania attorney general.

Is Northampton County District Attorney John Morganelli in the race to attack Montgomery County Commission Chairman Josh Shapiro in a coordinated effort with the third candidate, Allegheny County District Attorney Stephen Zappala Jr.?

Morganelli and Zappala deny any coordination.

Still, circumstantial evidence piled up as Shapiro labeled Morganelli's effort "a kamikaze campaign."

Zappala's hometown newspapers in Pittsburgh, the Post-Gazette and Tribune-Review, raised the questions about coordination in recent stories.

And there's this: John Fetterman, a candidate for the U.S. Senate and mayor of Braddock, said Zappala's nephew, Gene Peck Jr., told him in late February his uncle was coordinating against Shapiro with Morganelli.

Fetterman said Peck told him "the goal is to stick it to Josh," and laid out the effort this way:

"John chews him up in the east, and Steve spits him out in the west."

Fetterman said he found the tactic appalling. But he didn't say anything in public for five weeks because he worries that stepping into all this could have blowback for Braddock.

The small Allegheny County town sits less than 10 miles down the Monongahela River from Pittsburgh, where the Zappala family has built a powerful political operation.

Fetterman, who spoke to me Friday, said he agreed to come forward "with great reservation and sorrow," having known Zappala for several years.

Peck, a member of the Democratic State Committee from Allegheny County, did not respond to requests for comment.

Marty Marks, Zappala's campaign manager, said Peck is not in the loop on his uncle's tactics.

"He would have no way of knowing," Marks said. "He's not part of the campaign."

Marks said Zappala has aimed most of his fire at Shapiro because he is "our nearest opponent." Morganelli has done the same because he and Shapiro are competing for the same eastern Pennsylvania voters.

"It's practical politics," Marks said. "It's coincidence, not coordination."

Morganelli agrees that it makes sense for him to hit Shapiro in the east and calls claims of coordination "ridiculous." He points to a campaign ad that he says will start airing Monday that notes he has more prosecutorial courtroom experience than Shapiro or Zappala.

It's true that Morganelli has lightly rapped Zappala a few times on this point.

But that is nothing like the road-show he has taken to Norristown and Harrisburg lambasting Shapiro about campaign donations and calling for a state ethics investigation.

And the circumstantial evidence accumulates.

Morganelli has told some groups considering endorsements to go with Zappala if they don't pick him. He now says that's because the job of attorney general should go to a prosecutor, a post Shapiro has never held.

Morganelli, his party's nominee for attorney general in 2008, didn't even seek the Democratic endorsement this year.

About a quarter of the signatures Morganelli received on nomination petitions to get his name on the April 26 ballot came from Philadelphia. Morganelli said he hired an Allentown consultant to run his petition effort.

Two of the five petition circulators in Philadelphia for Morganelli have been paid by Local 98 of the International Brotherhood of Electrical Workers to run petition drives for other candidates for office.

"There were a couple of guys from Local 98, that's what I was told," Morganelli said.

The union and its leader, John "Johnny Doc" Dougherty, are backing Zappala in the race.

Dougherty also denies any coordination.

"I'm glad to see the people who have done stuff for us are doing work for others," Dougherty said of the petition circulators. "I hope they did really well."

215-854-5973@ByChrisBrennan