A former attorney for Martha Moxley murder suspect Michael Skakel has appealed a New York judge's order that he appear before the Connecticut grand jury investigating the Greenwich teenager's 1975 slaying.

The appeal, filed Jan. 11 by New York City attorney Thomas Sheridan Jr., seeks to overturn a Manhattan judge's ruling that Sheridan comply with the subpoena that had been issued by prosecutors in Connecticut.

Sheridan and his attorney, Norman Bloch, both refused comment yesterday. In his Dec. 18 ruling, New York Supreme Court Judge Herbert Adlerberg noted that Sheridan's testimony is being sought by a Connecticut prosecutor to challenge defense attorneys' claims that information pertaining to the Moxley case - obtained by private detectives while working for Sheridan - is privileged and cannot be put before the grand jury.

"Any claim regarding a violation of the attorney-client privilege, if indeed there is one, is to be litigated in the demanding state, which has been held by the Court of Appeals to be the appropriate forum to adjudicate such claims," Adlerberg ruled. "Accordingly, Thomas Sheridan is directed to appear and testify before the grand jury."

Although Adlerberg set Sheridan's grand jury appearance for Jan. 8, he also granted a 30-day stay on his own order to allow Sheridan time to file an appeal.

Grand jury testimony of investigators with Jericho, N.Y.-based Sutton Associates is being sought, according to an affidavit filed in Nassau County Court by Connecticut State's Attorney Jonathan Benedict, because of possibly incriminating information they obtained while working for Sheridan and another attorney representing Michael Skakel's brother, Thomas, who is also a suspect. In the affidavit, Benedict alleges that both Skakel brothers significantly changed the alibis they had given police in 1975 when they were questioned 18 years later by Sutton Associates investigators.

According to the affidavit, the revised stories placed the suspects either with Moxley or near the crime scene at about the time police said the 15-year-old girl was murdered with a golf club owned by the Skakel family. The suspects' father, Rushton Skakel Sr., is a brother of Ethel Skakel Kennedy, widow of U.S. Sen. Robert Kennedy.

Sheridan has said he represented Michael Skakel from 1976 until shortly after the Moxley grand jury was convened in June 1998. Stamford defense attorney Michael Sherman has represented Skakel since then.

Sheridan previously explained that he hired Sutton Associates in 1992 to investigate the Moxley murder and his client's possible involvement as preparation for a possible criminal defense. The following year, the agency was retained for the same purpose by Stamford attorney Emanuel Margolis, who has represented Thomas Skakel since 1976.

James Murphy, who owns Sutton Associates, and Willis Krebs, Murphy's former employee, both were subpoenaed to appear before the grand jury. An attorney representing Murphy and both Skakel brothers earlier this month successfully blocked the subpoena, with Nassau County Judge Jerald Carter ruling that Benedict failed to prove Murphy was a necessary and material witness. A hearing on an objection to Krebs' subpoena is pending in Suffolk County Court.

Since the grand jury was convened last summer, Michael Skakel apparently has emerged as the prime suspect. Among the witnesses to have appeared in the closed-door probe are former residents and staff members of a drug and alcohol abuse rehabilitation center where prosecutors allege that Michael Skakel made statements about the murder.