We now know police found out about it through a Letterman attorney, points out CBS News Correspondent Kelly Cobiella.
Halderman, accused of threatening to go public with word of affairs Letterman had with staffers of "The Late Show with David Letterman," has pleaded not guilty to attempted grand larceny charges. Letterman revealed the alleged plot, and admitted he'd had sex with employees, on the show.
The court documents say the lawyer told police Letterman, referred to only as "Client No. 1," received a package from Halderman "containing a demand letter, and a treatment for a screenplay," as well as portions of a diary, phone records and pictures belonging to someone whose name is blacked out.
Halderman allegedly wrote he had "a lot more" and that it would ruin Letterman's reputation.
There are reports one of the women involved is Letterman's former assistant, Stephanie Birkitt, who had been dating and living with Halderman.
In a search warrant signed Oct. 1, authorities say they want to look for computer hard drives, journals, pictures and screenplays to back up the extortion allegations. That same day, police searched the Norwalk, Conn. home Halderman and Birkitt had shared. Among the items removed: "copies of a check" and bank records, a computer and disc drives, and video and audio tapes.
The documents also spell out three meetings between Halderman and letterman's attorney, two of which police say they recorded.
At one point, Halderman allegedly says he's writing a book and threatens to reveal details of Letterman's personal life unless he's paid the $2 million.
Police say Halderman got a bogus check for that amount and deposited it, after which he was arrested.
More coverage on CBSNews.com
Photos: David Letterman
Letterman Case: Warrants to Remain Sealed?
Letterman Possible Former Lover May Be Key
Letterman Tossed Barbs From Glass House
Details Out on Supposed Ex-Letterman Lover
Letterman Apology A Ratings Hit
Expert: Letterman's Fate Far from Certain
Letterman Apologizes to Wife
Will "Other Shoes" Drop for Letterman?