PROVIDENCE — Two city police officers recently swore on the witness stand in federal court that they made few if any records of the surveillance and investigation of two men who were charged with being high-level crack dealers.

If there were any notes and records, they were discarded, testified Sgt. Scott A. Partridge and Detective Peter Conley.

But an astonished judge was told in court yesterday that there are copious records and that they had been stashed in the attic of Partridge’s house.

Given that the records had been withheld, a federal prosecutor moved to permanently dismiss the case against one of the alleged dealers, Khalid Mason, 31, who the police had called a prize catch in a joint city/federal undercover drug investigation dubbed Operation Crackdown.

U.S. District Judge William E. Smith, who called the story of the records in the attic “just incredible,” approved the dismissal. He said the records’ existence directly contradicts Partridge’s testimony.

Assistant U.S. Attorney Stephen Dambruch said Partridge “was mistaken” in his testimony but did not intend to mislead the court. When Partridge discovered the records — they include notes and signed reports of surveillance of Mason and co-defendant Derek W. Isom and records of checks of auto registrations — he presented them to his police superiors knowing that he would subject himself to criticism, Dambruch said.

Isom, 31, has pleaded guilty to charges in the federal case and is scheduled to be sentenced Sept. 6.

Mason was scheduled to stand trial, beginning yesterday, on criminal charges arising from Operation Crackdown. The belated discovery of the records last week “irreparably damaged” Mason’s constitutional right to due process of law, Dambruch said, and he asked to drop the case.

Dambruch hastened to add that the records actually buttress the government’s case against Mason or “at best they might be neutral” in their effect.

After the hearing at the federal courthouse at Kennedy Plaza, Police Chief Dean M. Esserman announced that he has ordered an internal Police Department investigation of the handling of the case against Mason and Isom and the work and testimony of Partridge and Conley.

Taking investigative notes and records home is a violation of department policy, Esserman said.

During questioning by defense lawyer Michael J. Connolly at a pretrial hearing last month, Partridge said he did not make surveillance reports; that he was not trained by the department to take surveillance notes but that he may have received some federal training in that regard; that the department did not issue him a pen and a pad to take notes but that he took some notes nevertheless, perhaps on a paper plate; and that he no longer has the notes. He also said there are no surveillance video or still photos.

Esserman said the U.S. Attorney’s office has agreed to help in the internal departmental investigation and that one possible outcome would be disciplinary action against police officers. Asked by a reporter if Partridge perjured himself, Esserman said he would await the results of the investigation before making a determination.

He said there will be no limits on the internal investigation and it may take in the wider issues raised by the Mason/Isom case.

Mason has claimed that his former lawyer, John M. Cicilline, colluded with a police officer to set him up with planted evidence, and that Cicilline demanded $100,000 each from him and Isom with the promise that Cicilline would use a corrupt police contact to fix the cases and get the charges dropped.

Cicilline is the brother of Providence Mayor David N. Cicilline and a son of widely known criminal defense lawyer John F. Cicilline.

Partridge, the officer who John M. Cicilline allegedly said he would contact in order to get the charges dropped, denied the allegations during last month’s hearing. Partridge, who is now a patrol sergeant but was a detective during the investigation of Mason and Isom, called the allegations insulting.

Connolly disclosed in court yesterday that the records found in the attic include at least 12 typewritten surveillance reports signed by Partridge. One was date-stamped in April, about three months prior to Partridge’s testimony. Connolly said the judge should punish the police for their misrepresentations regarding the evidence.

But Smith said the police are not legally a party to the case and he lacks that authority.

Mason and Isom were 2 of 104 people apprehended in Operation Crackdown. The pair were among nine who were singled out for federal prosecution, at least in part due to the larger amount of drugs they allegedly were distributing. That exposed them to longer prison sentences than they would have faced in the Rhode Island criminal justice system.

Regarding the dismissal of the case against Mason, Esserman said, “I don’t like it.” But he said it was called for “in the interests of justice.”

Mason faced a possible life sentence if he was convicted at trial on the three charges: conspiracy to distribute and possession with intent to distribute at least 50 grams of crack, and making available premises for the unlawful manufacture, storage and distribution of crack.

Mason and Isom have been accused of running a crack distribution ring, supplying lower level dealers, from a house at 214 Pavilion Ave., in South Providence. Mason previously was convicted of shooting a man — the victim survived — and of drug possession.

“Thank you,” a member of Mason’s family called out from the gallery of the court when it became clear that Mason was free of the charges, and a bailiff quickly moved in to hush the relatives. A number of family members wept in relief.

Doreen Mason, his mother, said later that she is focused on getting her son back. His father, Paul Price, said, “It’s been a good day. … My son came out OK.”

The U.S. Marshal’s office handed over Mason to Rhode Island deputy sheriffs, who had two outstanding arrest warrants for him: a criminal warrant charging him with two crack-dealing counts also stemming from Operation Crackdown and a Family Court civil warrant charging him with failure to pay child support.

Michael J. Healey, spokesman for Rhode Island Attorney General Patrick C. Lynch, said the state crack-dealing charges cover the same offenses as the federal charges, that they had been held in abeyance pending the federal prosecution, and that Lynch is now free to press them if he opts to do so.

Mason was taken to Superior Court in the afternoon, and Magistrate Patricia Harwood released him pending further court action.

gsmith@projo.com