New Haven - A man convicted of killing a former New Haven alderman and another man in 1990 should be released from prison unless the state decides to retry him, according to a federal judge who found authorities failed to disclose a claim that a detective had coached a key witness.

Judge Charles S. Haight Jr. ruled Monday that Scott T. Lewis should be released from prison within 60 days. A message left with New Haven State's Attorney Michael Dearington was not immediately returned.

Haight ruled the defense should have been told that a police lieutenant said the witness who implicated Lewis initially told him he knew nothing about the crime then later acknowledged the information he gave had been supplied by a detective.

Lewis has been serving a 120-year sentence after he was convicted of the shooting deaths of former Alderman Ricardo Turner and Lamont Fields.

Lewis and Stefon Morant were convicted of the killings. Morant was sentenced to 70 years in prison.

Lewis, who maintains his innocence, was represented by Columbia Law School professor Brett Dignam and her students.

"After 18 years Mr. Lewis is going to come home," Dignam said. "I don't think the state can reconvict Mr. Lewis with the new evidence."

The ruling also should help Morant, Dignam said.

Haight ruled that Lewis' defense should have been told about the account by former Lt. Michael Sweeney, who said the witness told him he knew nothing about the murders. Sweeney said a detective joined the interview and began giving the witness facts about the crime and the witness started changing his statement.

Sweeney later confronted the witness, who told him he was not telling the truth and that the detective was the source of his information, according to the ruling.

Sweeney said he told a supervisor about his concerns, but not prosecutors. Haight said he found Sweeney's account credible and concluded it was central to the credibility of the state's key witness and that Lewis' right to a fair trial was violated.

If the state decides to retry Lewis and the witness repeats his testimony implicating him in the killings, Sweeney's account will be available to the defense in challenging the witness' credibility, Haight said.

"That is the proper remedy for the state's violation of Lewis' constitutional right to a fair trial," Haight wrote.

Dignam and the students were assisted by Elora Mukherjee, who co-teaches the Mass Incarceration Clinic with Dignam.

"This is a rare victory," Mukherjee said. "Justice has been served for an innocent man. We look forward to welcoming Mr. Lewis home."