PLYMOUTH — A former Plymouth woman once dated the man who has been indicted in connection with a multimillion dollar blackmail plot against television personality David Letterman.

Stephanie Birkitt, 34, a 1993 Plymouth High School graduate, once dated and lived in Norwalk, Conn., with Robert J. "Joe" Halderman, who pleaded not guilty Friday in a Manhattan court to one count of attempted first-degree grand larceny, punishable by five to 15 years in prison.

Prosecutors said Halderman, a producer for the true-crime show "48 Hours Mystery," was desperate and deep in debt. He was released after posting $200,000 bail.

Birkitt is not accused in the extortion plot. Fox 5 news in New York, citing a search warrant, reported that Halderman used her personal diary and letters in his scheme to extort $2 million from Letterman. Birkitt was an assistant to Letterman on the "Late Show" and appeared on camera in comedy bits with the host.

Birkitt moved to Manhattan last month. There was no answer Saturday at a phone listed in her name. Efforts to reach her parents, who live in Plymouth, were unsuccessful Saturday.

Halderman wouldn't speak to reporters at his house Saturday morning and threatened to call police if they didn't leave the private road that leads to his three-bedroom home.

Letterman, on his show Thursday, acknowledged having sex with some of the women who have worked for him. It was unclear how many women were involved with Letterman, 62, who married longtime girlfriend Regina Lasko in March. The couple began dating in 1986 and has a son, Harry, born in November 2003.

All the relationships took place before Letterman's marriage, said Tom Keaney, spokesman for the comic's production company. Keaney also said Letterman "is not in violation" of the company's harassment policy "and no one has ever raised a complaint against him."

Halderman allegedly gave Letterman a package of materials that "contained clear, explicit and actual threats that indicate this defendant ... (wanted to) destroy the reputation of Mr. Letterman and to submit him and his family to humiliation and ridicule," Assistant District Attorney Judy Salwen said in court.

Halderman, hands cuffed behind his back, stared at the floor during most of the hearing and said only "not guilty."

His lawyer, Gerald Shargel, said Halderman worked at CBS for 27 years and had no prior criminal record. He described him as an involved father who coached soccer, baseball and football and has two children, ages 11 and 18.

"This story is far more complicated than what you heard this afternoon," Shargel said outside court, but would not elaborate.

Halderman allegedly left an envelope in Letterman's car early Sept. 9. According to authorities, he wrote that he needed money and said Letterman's world would "collapse around him" if damaging information about him were made public.

Letterman acknowledged that the letter contained proof that he had sexual relationships with members of his staff.

Three meetings between Letterman's lawyer and Halderman subsequently took place, the last two with the lawyer recording the conversations and prosecutors listening in, District Attorney Robert Morgenthau said.

At the last meeting, on Wednesday, the lawyer gave Halderman a phony check for $2 million, Morgenthau said.

Halderman deposited the check Thursday and was arrested that day, he said.