Police say Kittikun, who was wanted by police on five counts of burglary, initially gave confused statements as to how the death took place.
Kittikun, who was arrested in Soi Sukniran in Wichit, where he was living, told The Phuket News that he was acting alone when, on the spur of the moment, he decided to break into the girl's home, using a screwdriver to jimmy open a window.
Thinking no one was at home, he began to rummage around for items to steal when he heard noises from Ms Sunisa's room. He broke into it and a struggle ensued, during which her clothes became dislodged, he said. This stimulated him and he then held her face-down on the bed and attempted to rape her.
However, having taken drugs before going into the house, he was unable to complete his assault so, after ransacking the house, he left.
It was only later, he said, that he discovered she was dead.
Results of an autopsy on Ms Sunisa have yet to be completed, but police now believe that she suffocated while being held face-down on the bed by Kittikun.
Today Kittikun also admitted in a press conference that he was involved in robbing a florist in May this year.