Hartford officials say they cannot find a 30-year-old insurance policy that could play a key role in any damages or settlement the city would have to pay in a lawsuit filed by a man wrongly imprisoned for murder for two decades.

The inability to locate the policy prompted federal Magistrate Judge Joan Margolis in New Haven on Monday to order the city to subpoena insurance companies in an effort to find it.

Miguel Roman, of Manchester, filed the federal lawsuit against the city and police officials in March 2011, alleging malicious prosecution, suppression of evidence and violation of his civil rights. City officials deny the allegations. His lawyers have been seeking information on the city's insurance policies since the lawsuit was filed nearly seven years ago.

"Mr. Roman is satisfied that the court granted him the relief that he sought," said his lawyer, Rosemarie Paine. "The court's ruling provides a timeline for taking the necessary steps to locate the missing policy and move the case forward."

Nathalie Feola-Guerrieri, senior assistant corporation counsel for the city, declined to comment. She wrote in court documents that city officials have made many efforts to find the policy, including asking insurance companies to look for it, but to no avail.

Roman, 61, was convicted of murder in the 1988 killing of his 17-year-old girlfriend, Carmen Lopez, of Hartford, who was pregnant. Roman, who was not the father of the unborn baby, served 20 years of a 60-year sentence before being released in December 2008 and later exonerated based on new DNA testing that resulted in another man being convicted of her killing.

State officials later awarded Roman $6 million for his wrongful conviction.

The "excess" policy that is missing could be key in the lawsuit because it would cover any damages or settlement the city would have to pay above $2 million, which is the liability limit of the city's primary insurance policy issued by Travelers that was in place 30 years ago. Hartford struggled with its finances over the past year and was near bankruptcy before getting help in the new state budget passed in October.

Travelers has recommended to the city that it notify the carrier of its excess policy about the lawsuit, because of the chance that any award to Roman could exceed $2 million.

The excess policy presumably was in effect in 1988, when Roman said he was wrongfully arrested. An unanswered question in the case is whether the city's insurance policies in effect in 2011, when he filed his lawsuit, would cover any award to him.

Roman has not disclosed a specific dollar amount for the damages he is seeking.