Donald Gates was exonerated in 2009 through DNA testing after serving 27 years in prison. (Astrid Riecken/For The Washington Post)

A man who served 27 years in prison for a rape and murder he didn’t commit accused D.C. police of framing him, in the first federal civil rights claim for damages involving a wrongful conviction in the District.

All sides agree that Donald E. Gates, 64, is “stone-cold innocent,” as his attorneys put it, of the June 1981 murder of Catherine T. Schilling, a 21-year-old Georgetown University student assaulted and killed in Rock Creek Park after leaving the Watergate office building where she worked as a paralegal. But they disagree about whether police actions violated Gates’s constitutional right to a fair trial.

During a two-week trial, Gates’s allegation that two D.C. police homicide detectives and a lieutenant fabricated and withheld evidence has presented an emotional, legal and financial tangle to jurors, who began deliberations Tuesday.

Over days of testimony about regrets and missed chances, the panel has revisited the trauma of the crime and weighed police liability for Gates’s subsequent conviction while facing the prospect of deciding what value to place on lost decades of freedom.

The stakes for Gates and the District are high, although the court has barred any discussion of damages or amounts to the jury so far.

Police “had a hunch — a good hunch — that Donald Gates was good for the Schilling murder,” his attorney, Peter Neufeld, argued to jurors in the courtroom of Chief U.S. District Judge Richard W. Roberts.

“The problem is, when the detectives had that good hunch, they did the wrong thing. They crossed the line,” feeding Gates’s name and other incriminating details to a paid police informer who later testified, Neufeld alleged.

Shana Frost Matini, an attorney for the D.C. attorney general’s office, which is representing the defendants, agreed that imprisoning an innocent person for decades was among the worst things police could do short of killing him.

However, she said, any police mistakes were made because now-retired detectives Ronald S. Taylor and Norman Brooks and lieutenant John Harlow followed evidence in good faith.

“The evidence will show it is not these three police officers that caused the tragedy in this case,” Frost Matini said. Instead, the D.C. attorneys blamed a flawed FBI hair “match.”

Gates was exonerated in 2009 through DNA testing. He filed suit the next year, later learning that federal prosecutors found the real killer in 2012 after tracing genetic evidence at the scene to a convicted offender and temporary janitor at the Watergate who had died in 2011.

Although it was not part of this month’s trial, Gates’s innocence triggered investigations that led to exonerations of four additional men in the District who had served up to 30 years for rape or murder since the 1980s based on flawed FBI forensic testimony about hairs.

The FBI in April acknowledged that for more than 20 years before 2000, nearly every member of an elite FBI forensic unit overreached by testifying to the near-certainty of hair matches without a scientific basis. Defendants are now being notified.

However beneficial Gates’s exoneration has been to others, he would not have been prosecuted if not for the police informer’s account, according to testimony last week from the original prosecutor, J. Brooks Harrington.

Revisiting the circumstances of Gates’s conviction triggered strong emotions at trial.

Gates declined an interview request and indicated that he has had panic attacks at being in a courtroom with police defendants for the first time since his conviction. He now walks with a cane because of an arthritic hip and lives near his sister’s family in Knoxville, Tenn.

Several witnesses said they have been unable to forget the case. One woman who was part of a search party after Schilling went missing recalled the horror of discovering her nude body, shot in the head, in a grassy area near Rock Creek Parkway and Virginia Avenue NW.

Brooks, who had been Taylor’s junior detective partner, hinted at the strain of Gates’s allegations during a courtroom break, saying, “This is killing me,” before declining to further comment, as did his co-defendants, until the trial concludes.

According to Gates’s attorneys, police seized on Gates as a prime suspect within days of Schilling’s murder. They presented evidence that included a 1982 government legal brief and June 1981 arrest warrant that said police knew about Gates because he had been caught during a drunken purse-snatching attempt on a towpath near the Schilling crime scene on June 3 — three weeks before Schilling’s killing.

Detectives said the first time that they heard Gates’s name was June 30, when they met with Gerald “Bear” Smith, an informer who was paid $1,300 by police after they said he named Gates as a drinking companion who confessed to robbing, raping and then killing a young woman.

Both sides clashed over whether it was more likely that Smith knew Gates and concocted the false confession himself or had been fed Gates’s name and investigators’ theory of the case by police.

“I never saw that man in my life,” Gates said about the informer. “Never saw him. Never spoke to him.”

The police defendants denied in court that they gave the informer Gates’s name, although they gave conflicting accounts of their dealings with him.

Taylor said he never expected the informer to be asked to testify because it would blow his cover. He, Harrington and Gates’s defense attorney, Hamilton “Phil” Fox, each said it was the only time in their careers a police informer became a witness.

“Mr. Smith’s information was used only as a tool to give us a direction to go,” Taylor said. That information would need to be substantiated, he said, “which this was in the case of Mr. Gates, unfortunately, by the FBI laboratory.”

Under federal law, Gates was awarded a flat, $50,000 per year for the U.S. government’s role in his wrongful incarceration, or nearly $1.4 million, an amount that did not take into consideration police misconduct.

If jurors decide that D.C. police separately violated Gates’s constitutional rights, they could award damages in a second phase of the trial.

In one of two recent civil rights claims in New York brought by individuals exonerated by DNA, a federal jury awarded $41 million to Jeffrey Deskovic, who had served 16 years after a sheriff’s investigator allegedly fabricated evidence. His award was limited to $10 million by a pretrial agreement. In the other case, a federal jury awarded $18 million each to John Restivo and Dennis Halstead, who served 18 years after a detective allegedly planted and withheld evidence.

In Deskovic’s case, two other police agencies earlier settled related litigation for an additional $12 million, according to news accounts.