Finau tried the back door but it was locked and as he walked around the side of the house he fell into the swimming pool.
Finau went through an unlocked ranchslider, stripped naked and walked upstairs where the woman was sleeping. When the woman woke she told Finau she had money in her purse and took him downstairs and tried to get him out.
He physically assaulted her and sexually violated her a number of times throughout the attack.
After dressing himself in her clothes, Finau forced the woman downstairs to the garage and made her show him where her car keys were. He tried unsuccessfully to force the woman into the laundry and she tried to escape.
From that point she remembers nothing but Finau told police he beat her. Eventually she crawled on her hands and knees to a neighbour's house.
Finau stole the car and members of the public alerted police to his erratic driving. Police chased him, eventually stopping Finau in Wellsford.
Since the attack the woman had had surgery and plastic surgery and had lost her sense of smell. She was unable to eat solid food for eight weeks and had been left disfigured.
Finau had been in New Zealand since 2006. He was married with a six-year-old boy but the wife is with their son in Tonga.
Crown prosecutor Mike Smith said preventive detention was applicable in this case because of the violence, direct sexual attacks, the use of weapons and the home invasion.
"This was a truly terrifying crime committed on a member of society that deserves protection," Mr Smith said.
Defence layer Richard Garbett said Finau lost two jobs in New Zealand because of his substance abuse.