Ever since the Brooklyn district attorney accused a decorated FBI agent of helping his mob informant murder his rivals, there has been much bitter talk about the case. This week, Gang Land heard the worst yet: One insider was called “a slime bag.” Another was accused of having “delusions of grandeur.” A third had “radical mood swings.” One was said to be so dangerous that the Department of Homeland Security had been notified about him.

But the oddest thing about these nasty attacks is that none of them involve attorneys or investigators on either side of the case. Rather they emerged from a series of catty e-mails from three would-be crime busters who each claim credit for helping to assemble the evidence that led to the indictment of a former FBI supervisor, R. Lindley DeVecchio.

The trio, a pair of writers and a self-styled forensic analyst, has been ripping into each other in vicious e-mails that question the others’ motives and tactics going back to the early stages of the investigation, Gang Land has learned.

In some of the e-mails, sent as the grand jury probe was beginning in early 2006, the authors, Peter Lance and Sandra Harmon, and the analyst, Angela Clemente, direct their venom at each other. In others, they vent their anger at each other to the assistant district attorney who spearheaded the investigation that led to the indictment that charged the former G-man with helping his murderous mobster-informer, Gregory Scarpa Sr., kill four victims between 1984 and 1992.

The e-mails are legally important not for their scathing comments but because they appear to demonstrate that the three decidedly pro-prosecution gadflies, who each had access to Mr. DeVecchio’s immunized testimony, were intimately involved with the investigation that led to his indictment in March 2006.

By September 2005, the e-mails show, Ms. Clemente and Mr. Lance had shared information they had obtained about Mr. DeVecchio with prosecutors working for the Brooklyn district attorney, Charles Hynes. They also show that by December 26, 2005, Ms. Harmon was supplying information to Mr. Hynes’s office.

At a pretrial hearing that began yesterday afternoon in state Supreme Court in Brooklyn, the burden is on Mr. Hynes’s office to prove to Judge Gustin Reichbach that prosecutors did not, directly or indirectly, use any of Mr. DeVecchio’s immunized testimony to make their case against the retired FBI agent.

On January 11, 2006, a few days after news stories about the investigation first broke, Ms. Clemente wrote an e-mail to a prosecutor then working on the case, Noel Downey, warning him that both Mr. Lance and Ms. Harmon “will be damaging” to the investigation. “Peter is a dangerous person whom I have had to report to Homeland Security in the recent past. Be extremely cautious of him,” she e-mailed Mr. Downey, a former chief of the Brooklyn district attorney’s Rackets Bureau, according to court papers filed with Reichbach.

In a retort sent to Mr. Downey two hours later, Mr. Lance wrote that “a source whom I trust” had alerted him that either Ms. Harmon or Ms. Clemente, or Ms. Clemente’s associate, the late Stephen Dresch, had been “badmouthing” him. Uncertain about the identity of the culprit, Mr. Lance lambasted all three of them as “fringe players,” placing a special emphasis on Ms. Clemente. Ms. Clemente “exercises radical mood swings” and “utter unpredictability,” Mr. Lance wrote, adding that even though he “wined her and dined her multiple times” and “done my best to understand the demons that haunt her, like many sources she is unpredictable and thus untrustworthy.”

In a later complaint to Mr. Downey about Ms. Clemente, Mr. Lance reminded Gang Land of the old saw about the pot calling the kettle black.

“She now appears to be suffuring [sic] from delusions of grandeur” and “preventing me from getting evidence that could be helpful to you,” he wrote in one of the many e-mails the beleaguered prosecutor seems to have sloughed off or totally ignored, according to the filings.

Ms. Harmon is “also subject to radical mood swings” and her only prior notice before Mr. Lance “legitimized” her with a mention in his book “Cover Up: What the Government Is Still Hiding About the War on Terror” was as “co-author with Pricilla [sic] Presley of ‘Elvis and Me,'” he wrote in a long missive in which he credited his own work with being the basis of the district attorney’s investigation. (Mr. Lance has also expressed displeasure about several Gang Land reports, but — you’ll have to trust me on this — has had no impact on this column. Anyone seeking to read his opinion about Gang Land can check out Mr. Lance’s Web site.)

For her part, Ms. Harmon — who is currently writing a book with Gregory Scarpa Jr., a likely trial witness against Mr. DeVecchio — told Mr. Lance in an earlier e-mail that she was working with Mr. Hynes’s office and had firsthand knowledge that “nobody at the DA’s office gives a flying crap” about him or his work.

Ms. Harmon wrote that she could “hardly wait” to complete her book and expose Mr. Lance as a self-promoting “slime bag” on radio and TV during her book tour. “I am very attractive and funny and articulate and am just great in the media,” she wrote.

Finally, Ms. Clemente — whose input in the investigation was cited at a news conference about the sensational indictment by Mr. Hynes’s chief prosecutor, Michael Vecchione — complained to Mr. Downey in several e-mails that Mr. Lance was undercutting her investigative work.

In late January 2006, after Ms. Clemente asked Mr. Lance to “relax” and let the investigation proceed without his interference, Mr. Lance had fired off a dismissive 2,500-word “cease and desist” reply that extolled his own virtues and importance, sending a copy along to Mr. Downey asking him to take his side in the escalating feud. “Help!” Ms. Clemente retorted in an e-mail to Mr. Downey. “This guy is highly delusional and I think he actually believes what he is saying,” she added, thus getting the last word in the e-mails that were obtained by Gang Land.

DISAPPEARED MEN TELL NO TALES

Carmine Sessa, the one-time mob consiglière who first blew the whistle on the allegedly corrupt relationship between Mr. DeVecchio and Scarpa Sr., is one of several Colombo turncoats who testified before the grand jury that indicted the former G-man.

But being a trial witness may not be in the offing for the oft-troubled Sessa, who has been treated for depression and suicidal tendencies, and was arrested several years ago for punching his wife while living under the auspices of the Witness Protection Program. Last year, Sessa signed himself out of the federal witness program, and law enforcement sources say he hasn’t been seen or heard from since. Some officials have expressed concern over Sessa’s current status, but another speculated: “He may have just decided to start fresh somewhere and leave his old life behind.”

A CORRECTION AND A SAD CONFIRMATION

Two weeks ago, Gang Land disclosed that 10 years after mob associate Richard Guiga was killed by two cohorts, his loving mother, Rosanna, would finally be able to give her son a proper burial because authorities learned that his remains were in Potter’s Field.

In reporting that, however, Gang Land unintentionally caused Guiga’s long-suffering 74-year-old mother additional grief by reporting that her late husband, Sal, had disowned her son because of his criminal ways.

Not true, Mrs. Guiga, a retired schoolteacher, said. “Richie was no angel, but his father loved him dearly. He didn’t like the life Richard chose, and they had father-and-son arguments, but he never disowned him; he always loved his son,” she said.

Richard’s body has not yet been exhumed, but based on what FBI agents have told her, Mrs. Guiga said she expects to bury her son within a month.

She also lives with the confirmation of her worst fears about her son’s death: That his alleged killers, Nicholas “P.J.” Pisciotti and Michael DeMaria, were longtime friends whom she taught in class. “I knew it a long time. I don’t want to get into it,” she said. “I had DeMaria and Nicholas in my class. I taught them how to write and read.”

This column and other news of organized crime will be available today at ganglandnews.com.