Ted Kergan never stopped searching for answers to the 1984 disappearance of his brother, Gary Kergan, even when two primary suspects were released from jail in 1985 because of a lack of evidence.

But thanks in part to his persistence — and DNA testing methods developed since his brother’s presumed murder — the same two people originally arrested were taken back into custody on Monday.

Ronald Dalton Dunnagan, 64, of Bossier City, and Leila Mulla, 47, of Astoria, N.Y., were arrested with help from the Bossier Parish Sheriff’s Office, the New York Police Department and the Queens, N.Y., District Attorney’s Office, Baton Rouge Police Department spokesman Lt. Don Kelly said.

The two are again being accused of conspiring to rob Gary Kergan nearly 30 years ago.

The new link, Kelly said, is a recent DNA test of blood found in Kergan’s abandoned car that the State Police have confirmed belonged to Kergan. Baton Rouge Police Chief Dewayne White declined comment when asked Monday whether any other DNA evidence could link Kergan’s disappearance to Dunnagan and Mulla.

“I’m very, very happy that it appears that the people that did this are going to be brought to justice, and I am very, very sad, as I always have been, that these scum of society ever chose to take my brother’s life,” Ted Kergan said in a telephone interview Monday.

Gary Kergan, a Crowley businessman who along with his brother owned a chain of Sonic Drive-In restaurants in Louisiana, was last seen alive Nov. 29, 1984, at Mulla’s north Baton Rouge home, Kelly said.

Kergan’s car was later found abandoned in Metairie, but his body has never been found. He was declared legally dead by the courts in 1986, Kelly said.

Authorities found a significant amount of blood in the trunk of Kergan’s car but at the time could not determine definitively at the time whether it was Kergan’s because the technology was lacking, Kelly said.

Dunnagan, who was described in news accounts at the time as a drifter, and Mulla, a 19-year-old exotic dancer, were originally arrested Dec. 7, 1984, in Las Vegas and shipped back to Baton Rouge for prosecution.

However, then-District Attorney Bryan Bush declined to prosecute the pair because of a lack of evidence — specifically, no body. Mulla and Dunnagan were eventually released in March 1985.

Ted Kergan said Monday that he has kept in touch with authorities about the case for years because the memories of his brother’s death never left him.

“When people ask me that question, I kind of throw it back. I say, ‘Well, what would you do if it was your brother, or one of your kids?’ ” he said. “And the answer is you would do anything, and you would never give up.”

The case took a positive turn sometime around March, shortly after White reorganized the Baton Rouge Police Department’s cold case division and named Cpl. John Dauthier as its lead investigator.

Dauthier began reviewing files and looked for homicides that had a high probability of being solved. Kergan’s death was among those files, White said Monday.

The department had preserved evidence from the original case and had a family member — whom Ted Kergan confirmed was Gary Kergan’s son Wade — provide a DNA reference sample, White said.

The blood was recently re-tested at the Louisiana State Police Crime Lab. The analysis showed it belong to Kergan.

Investigators traveled to Bossier City and Astoria, N.Y., this week to question Dunnagan and Mulla, Kelly said. Both were rearrested Monday and will be returned to Baton Rouge to face prosecution.

Dunnagan was booked on counts of first-degree murder, simple robbery and criminal conspiracy. Mulla was booked with second-degree murder, simple robbery and criminal conspiracy.

White said one of the two suspects is cooperating with authorities. He declined to say whether it was Dunnagan or Mulla.

White said he is confident similar arrests in other cold cases will be made in the future. “I can almost promise it,” he said.

District Attorney Hillar Moore III agreed.

“It is unusual that someone is arrested for a crime and then 20 years later they’re rearrested,” he said. “But with the advent of technology and with the new cold case section, I think that this is something you could possibly will see more of, particularly based on scientific evidence.”

Moore said that while he is still reviewing the facts of the case, it is likely it will be sent to a grand jury.

For now, all parties involved are still left with one other issue: no body. White said authorities are “cautiously optimistic” it can be found.

Asked about the likelihood of winning the case without having a body, Moore said: “Obviously, we would rather have a body, because on a body you would have evidence that you could collect, and in this case we don’t.”

He continued, “But that surely does not mean that we can’t prosecute the case and someone cannot be found guilty just because there’s no body.”

Ted Kergan said he doesn’t believe finding his brother’s body should matter to the case.

“I think it’s just like putting a puzzle together, and at some point you just say, ‘Hey, that’s what this puzzle is,’ whether you have all the pieces or not,” he said.

Editor’s note: This article was changed on Dec. 4, 2012, to correct the age of Leila Mulla.