Enceng Kurniawan, one of two killed terrorist suspects in Aceh, was actually a former convict on the 2004 Australian Embassy bombing.
Enceng was arrested in 2005 and got six years imprisonment by the South Jakarta District Court.
The Supreme Court in 2007 rejected the appeal filed by prosecutors and decided Enceng's sentence stayed at six years in prison.
Enceng left the prison last year, observer said, after serving only five years in prison due to a number of remissions given to him.
Noor Huda Ismail, the director of the Institute for International Peace Building, also known as a terrorism researcher, confirmed the matter.
"I was a close friend of Encang's. Yes, he got remissions and left the prison before serving all the six-year imprisonment," Noor told The Jakarta Post.
However, Noor said he lost contact with Encang since months ago. "I don't know when he entered Aceh," he said.
Encang and his colleague Pura Sudarma were killed in Friday last week during a 30-minute gunfight with the police in Aceh Besar, Nanggroe Aceh Darussalam.
The police arrested eight other suspects during the raid.