BANGOR, Maine — A man incarcerated in South Dakota was indicted Wednesday by the Penobscot County grand jury in the fiery death of a transient four years ago.

Kenneth John Bruning, 25, of Rapid City, S.D., was indicted on the charge of intentional or knowing murder.

The body of Trevor Sprague was found facedown and on fire under the Harlow Street Bridge on March 7, 2006. The 34-year-old Lubec native and Bangor transient was known to camp along the Kenduskeag Stream.

Bruning is being held at the Pennington County Jail awaiting trial on burglary and theft charges, according to Bangor police. It is unlikely he would be returned to Maine until the case there is resolved.

Information on when he went to South Dakota or how long he has been there was unavailable Wednesday.

Lt. Tim Reid, who heads the Bangor Police Department’s detective division, provided no new details about how or why Sprague died at a press conference late Wednesday after the grand jury handed up the indictment.

He said that members of Sprague’s family in Lubec and Florida had been notified of the grand jury’s decision.

Details about the circumstances surrounding his death and what led investigators to Bruning will be released when Bruning is returned to Maine to face the murder charge, Reid said. The lieutenant said he did not know when that would be or if Bruning would waive extradition to speed the process.

Bangor police confirmed that Bruning was a member of Bangor’s transient population when Sprague was killed and that Bruning was charged in an unrelated assault at the former Acadia Recovery Center, now the Hope House, two weeks after Sprague died.

Bruning was convicted of that crime and fined $300 in October 2009, according to court news published by the Bangor Daily News.

Smoke coming from under the concrete-and-metal bridge over the Kenduskeag Stream on Harlow Street on March 7, 2006, caught the attention of a passing driver, who called the Fire Department, according to previous reports. When firefighters and police arrived at the bridge, they found Sprague’s body along the bank of the stream in flames 2 feet high.

At 6 feet 7 inches, Sprague was a tall man, and his feet, sneakers and the lower part of his body could be seen from the riverbank, a police officer reported at the time. His body was burned so badly that investigators had to use DNA to positively identify him, according to previous reports.

Reid said Wednesday that although it was “unusual” to indict a defendant on a murder charge four years after the victim died, it was not “unheard of.”

“This case was very solvable,” he said. “We were very confident that it would be solved. There was a lot of anxiety in the community after Trevor Sprague’s death, especially in the homeless population. A lot of that can be put to rest now with this indictment.”