The man who killed Christchurch woman Renee Duckmanton is trying to appeal his murder sentence.

Sainey Marong is representing himself in the Court of Appeal this morning in front of members of Renee Duckmanton’s family.

He is serving a minimum of 18 years in prison after the 22-year-old's body was found burnt on the side of the road in Rakaia in 2016.

Marong admitted to killing her, but claims he had a disease of the mind at the time. He also believes his trial was a miscarriage of justice.

Speaking in the third person, he told the court he was diagnosed with "adjustment disorder" and put on medication after his arrest.