"Am I cuckoo? Am I cuckoo? I'm not," he insisted, claiming Doyle was alive when they set out for the post office but may have died on the way.
"We were grand then all of a sudden he started going all slumpy."
Haughney, who served two years in jail for fraud after stealing his aunt's bank card, said he was assaulted by locals who blamed him for the death after the story broke - but has put his past behind him.
"I'm off the gear three years and doing well," he said.
The police investigation remains open, as locals struggle to come to terms with the bizarre incident.
Fergal Brown, a Fine Gael councillor, said the incident was "very upsetting for everyone locally".
Carlow Mayor Ken Murnane said the allegations had left townspeople in shock.
"It's just mind-boggling that anyone could happen to do something like that," Murnane said. "It beggars belief. It's like a Hitchcock movie."