Suffolk County District Attorney Thomas Spota and one of his top aides have been indicted on charges that they obstructed a federal civil rights investigation into the beating of a handcuffed prisoner by a police chief.

Suffolk County District Attorney Thomas Spota and the chief of his anti-corruption bureau, Christopher McPartland, were named in an indictment charging them with obstruction of justice, witness tampering and other offenses related to the case against former county Police Chief James Burke.

Sources told NBC 4 New York they surrendered Wednesday afternoon. They were scheduled to appear in court later in the day. 

The charges against Spota, 76, and McPartland, 51, relate to an FBI investigation that led to the conviction of former Suffolk County Police Chief James Burke.

Burke is serving prison time for beating a handcuffed man for stealing embarrassing items from his SUV. He pummeled the heroin addict who had taken his gun belt, ammunition, a box of cigars and a bag containing sex toys and pornography, prosecutors said.

“While FBI agents were working to restore justice in a civil rights investigation, (the defendants) were conspiring to obstruct it,” William Sweeney, Jr., assistant-director-in-charge of the FBI’s New York field office, said in a statement Wednesday.

In a pre-sentencing letter, prosecutors said "high-ranking officials" from other county agencies helped Burke silence potential whistleblowers after he pummeled a heroin addict who had taken his gun belt, ammunition, a box of cigars and a bag containing sex toys and pornography.

Officers subpoenaed by FBI agents investigating the 2012 beating were interrogated afterward about whether they had talked, prosecutors said. Unnamed co-conspirators had warned some that if they admitted wrongdoing, their union would not pay their legal fees, prosecutors said.

According to the indictment, Spota, McPartland, Burke and other police officers had numerous meetings and telephone conversations discussing the assault of "John Doe" and how to conceal Burke's role in the assault.

The defendants used their authority "to obstruct and attempt to obstruct the federal investigation by, among other means, using intimidation, threats and corrupt persuasion to pressure multiple witnesses, including co-conspirators, not to cooperate with the federal investigation, to provide false information, including false testimony under oath, and to withhold relevant information to prosecutors," the court paper said.

In a bail letter, Acting U.S. Attorney Bridget Rohde wrote that "the strength of the evidence in this case is overwhelming and consists of dozens of witnesses, including current and former members of the Suffolk County Police Department and Suffolk County District Attorney's Office, who will detail the assault of John Doe and the long-standing and far-reaching obstruction of justice conspiracy spearheaded by (the) defendants." She said evidence includes telephone call records, cell site records, police records, financial records, and photographs. 

There was no immediate response to messages left Wednesday seeking comment from the men's attorneys.

A spokesman for the district attorney's office had no comment.

Spota, a Democrat, was elected 16 years ago and is not running for re-election.