The South Australian detective who collared outback killer Bradley Murdoch has spoken for the first time.

Geoff Carson explained to 9News how he connected a mysterious individual in the Riverlands to the killer of Peter Falconio and revealed his theory regarding what Murdoch did with the backpacker’s remains.

Now retired, Carson was the small-town cop who solved a national mystery.

“I said I reckon I got your fella,” he said.

But NT Police had already crossed Murdoch off their list.

So Carson took matters into his own hands.

He bundled up cigarette butts and milk cartons marked with the killer’s DNA, evidence that would lead to a match and a warrant for Murdoch’s arrest.

For the Riverland rapes a jury found there wasn’t enough evidence to convict Murdoch.

But on the day he was acquitted police were waiting at Adelaide’s Supreme Court.

The monster was charged for an outback murder.

But Carson remains determined to solve that mystery once and for all.

He says he was given one clue, a remark Murdoch had made to a friend.

“He mentioned to this old man, ‘If I were ever to dispose of a body, I would place it into the grate by the roadside, like in the flood mitigation area, and bury it there because no one would ever discover it, no one would ever dig in that spot’,” Carson remarked.

Falconio’s remains may still be missing but the case isn’t closed.  

The reward for information was recently raised to $500,000.

“Anyone who has lost a loved one wants to be able to put that loved one to rest,” Carson said.

“They want to know that they are finally at peace, the Falconio’s haven’t got that.”