A Northern Virginia woman who has served time in jail is making allegations against Vanity Fair writer Dominick Dunne after warning him that she would go to the press if he didn't pay her nearly $100,000.

"As God is my witness, I'm gonna go public. . . . Now the only thing that's gonna keep me from going public is I want what was promised to me," Martha Jane Shelton said in a rambling message left on Dunne's voice mail on April 24, according to a transcript of the call. She added: "If you want to keep it out of the media, you know, just deliver on your promise. . . . If not, I'll see you in the news."

Asked in an interview about her demands for payment from Dunne, Shelton said: "I guess it could be construed as a threat. . . . I know it sounds like I'm trying to bully him or shake him down. But he made me promises."

She said those promises of cash -- which Dunne strongly denies making -- stem from her assistance on Vanity Fair articles a decade ago. In recent weeks, after Dunne ignored her demands, Shelton called attorneys for former representative Gary Condit and offered to assist in his $11 million defamation suit against Dunne over remarks related to the disappearance of Chandra Levy. Shelton also cooperated with a New York Post article last month and then called The Washington Post to publicize her allegations.

Dunne acknowledges that he has paid Shelton $1,600 over the years, which he characterized as helping out a friend. "There was always a hard luck story," he said in a statement, such as her getting fired or facing eviction. "On my word of honor, I never paid her for information and I never asked her to lie. I never got any great information from her."

Dunne, 78, is a novelist, Hollywood hobnobber and celebrity court chronicler who has covered the trials of O.J. Simpson, William Kennedy Smith, Claus von Bulow and the Menendez brothers.

Shelton, 40, says she carried out a threat to call Vanity Fair Editor Graydon Carter and angrily told him of her allegations. But Vanity Fair spokeswoman Beth Kseniak, noting that the magazine supports Dunne completely, says Shelton never reached Carter and ranted at an assistant.

Shelton sent a reporter copies of America Online e-mail messages she says were from Dunne, who insists they are bogus.

On March 23, Dunne purportedly wrote: "You really need to be careful about giving up any information about the deal you and I had. I know you feel that I have turned my back on you in terms of financial help. I know I made promises that I did not keep. . . . You will get the money I promised, however my dear you need to keep up appearances. No one must know what you and I discuss."

According to e-mails provided by Dunne's attorney, Laura Handman, the two did exchange notes about an hour earlier. Shelton wrote that she was "getting ready to go public with my real story. . . . I know in your book, I always have been and always will be a loser. At this point I don't care. I am crazy, I know that. Please don't take any of this personally."

In a short return note, Dunne wrote that "in my book, you have never been a loser," adding: "I think you have every right to go public." Some of Dunne's words in that note were included in the disputed e-mail provided by Shelton, along with more incriminating language that Dunne contends was fabricated.

"I did not reply to the sleazy e-mail and never asked her to get any information about Gary Condit," Dunne said, adding: "On my word of honor as a lapsed Roman Catholic, I did not write these e-mails. Is this not a form of forgery? I am horrified that I have been put in this terrible position." The voice mail messages left for Dunne are related in what his attorneys describe as a transcript of Shelton's calls.

Shelton -- who says Dunne has paid her $6,100 but does not have copies of the checks -- wants Condit's lawyers to authenticate the e-mails by obtaining a laptop she previously owned. Lin Wood, Condit's chief attorney, says he is investigating Shelton's claims.

"Whether her accusations are credible and will be relevant to the lawsuit by Congressman Condit remains to be seen," Wood says. He says he is "proceeding cautiously," both because of "some limited information I have about Ms. Shelton and her background" and because "I would not want to do to Dominick Dunne what he did to Gary Condit" by repeating uncorroborated accusations.

But Handman expresses confidence that the case will be thrown out "when the court looks at what Mr. Dunne did to follow up on information at a time when Ms. Levy's remains had not been found, when her murder was -- and still is -- unsolved."

On one point, there is no dispute: Shelton has been in and out of court over the years. She served time in jail -- more than a year, she says -- for passing bad checks in the late '80s and early '90s.

Last year, according to court documents, an arrest warrant was ordered for Shelton, but never served, in a Bucks County, Pa., case charging her with harassment. A police officer's affidavit in the case says Shelton engaged in "stalking/harassing activity" by sending e-mail messages under two other identities -- in one instance charging that a man who was the target of her ire "had sexual relations with her under-aged sister." Shelton disputes some of the details but concedes she sent the man an e-mail saying "I was going to have my sister's big black boyfriend beat his [butt]."

Asked about two other Virginia cases involving charges of assault or harassment, Shelton says that "I cuss people out." In one case involving a former office colleague, "we were fighting over a guy that worked at the same company. . . . I pled guilty to that because I actually did threaten her over the phone."

Shelton first became a source for Dunne after striking up a telephone friendship with Lyle Menendez, one of the brothers accused of killing his parents. In April 1994, Dunne quoted Shelton in Vanity Fair as saying that the jailed Menendez had told her he had "snowed half the country" in winning a mistrial. The Menendez brothers were ultimately convicted.

Shelton now says she concocted that story at Dunne's request and that he promised her a $100,000 reward. After years of friendship, she says, Dunne again sought her help when Condit sued him over statements tying the congressman to the 2001 death of Levy, a former congressional intern.

A federal judge in April refused to dismiss the case. The suit cites comments by Dunne on radio and television shows, such as "Larry King Live," that Condit rode with the Hell's Angels and that a Condit friend might have taken Levy away on a motorcycle. Dunne -- who cautioned he could not vouch for the accuracy of the stories -- also reported hearing that Condit had complained at sex parties at Middle East embassies that Levy was a "clinger" who threatened to go public with information about him.

Shelton says she does not know Condit, but that when she mentioned she had dabbled in the world of S&M sex, Dunne asked her to make up some items that would tie the former congressman to that scene.

She acknowledges that she has long had financial problems in trying to support her son and two disabled relatives. "I know I come off sounding like a horrible person," Shelton says. "Really, I'm not. I've had a troubled past."

High-Flying Journalism

Are any media types crazy enough to chase a story by jumping out of a plane?

Brit Hume fits the description. The Fox News anchor did a parachute jump yesterday, shortly before George H.W. Bush did so too, and then interviewed the just-turned-80 former president.

"We reporters are supposed to be up for stuff, aren't we?" Hume, 60, said before taking the plunge. "It's kind of an adventure." He said he determined after Bush invited him that "the level of peril in this was not overwhelming."

Vanity Fair writer Dominick Dunne denies promising cash for information.