Assistant District Attorney Mark Dwyer suggested to ABC News that the alleged extorter was careless. "If I were extorting somebody I wouldn't want a check," he said.
Dwyer said that it in cashing the check, Halderman "was going to pretend it was the legitimate sale of a screenplay."
Halderman lived until recently with Stephanie Birkitt, 34, who had previously been a personal assistant to Letterman. Public documents indicate that Birkitt and Halderman lived together in Norwalk, Conn., from August 2005 to August 2009. Birkitt now has an apartment on Manhattan's Upper West Side.
Halderman has been married and divorced twice, according to public records. He had two children with his second wife as well as three step-children. His ex-wife won custody of the children and now lives in Colorado.
Divorce records show that Halderman was ordered to pay $6,800 a month in alimony and child support starting May 1, 2004. That would mean that to date Halderman has paid a hefty $442,000 to his ex-wife.
Halderman's lawyer Shargel has defended some of the city's most prominent criminals, including notorious mafia don John Gotti. Halderman's most recent assignment at CBS News was to produce a "48 Hours Mystery" piece on Gotti family.
"I'm doing everything necessary and appropriate to get him out," Shargel told ABC News. The lawyer said he has no prior relationship to Halderman.
Letterman, 62, confessed during a taping of "The Late Show" for broadcast Thursday night that he had had sex with members of his staff.
"This morning I did something I've never done in my life," Letterman told his audience. "I had to go downtown and testify before a grand jury."
Letterman revealed to the studio audience that he received a package three weeks ago containing a threat to reveal those indiscretions "if Letterman did not pay the individual a large sum of money" -- specified in a later communication as $2 million.
He said that the package contained a letter that said, "I know that you do some terrible terrible things, and I can prove that you do these terrible things ... and sure enough what was contained in the package was proof that I do terrible, terrible things."
The audience laughed nervously as Letterman described how he'd called his attorney and then set up a meeting with his blackmailer in which the plotter told him he wanted to write a screenplay about him that included sordid details of the talk show host's life.
At a third meeting, Letterman, with the assistance of the Manhattan District Attorney's Office, handed the blackmailer a phony $2 million check. It was then that the extortionist revealed he also planned to write a book about Letterman's life, also revealing details of his past sexual infidelities.
"A companion piece to the screenplay," Letterman cracked weakly.
Letterman then acknowledged unspecified sexual relationships with female staff members to a silent audience.
"My response to that [allegation] is, 'Yes I have.' Would it be embarrassing if it were made public? Perhaps it would," Letterman said.
"Especially for the women," he managed to joke.
"I feel like I need to protect these people. I need to certainly protect my family," he said.
CBS News released a statement saying that he has been suspended from his job as the investigation continues.