New Witness in Nicollette Sheridan Trial May Be Smoking Gun

A new witness has surfaced in the Nicollette Sheridan trial who could raise the specter of a cover-up.

Nicollette's lawyers told the judge today ... they have a witness -- a low-level employee on the set of "Desperate Housewives" -- who said he was mistakenly added to an ABC email which said it was using the network's IT department to wipe everyone's hard drives of all communications relating to the demise of Nicollette's character on the show.

ABC lawyers were stunned, saying they had no knowledge of such a witness or an email.

Nicollette's lawyers told the judge ... the email indicates there was "definitely a conspiracy to cover up correspondence."

You'll recall, Marc Cherry has said he was noodling on the idea of killing off Nicollette's character months before he laid a hand on her.