De Gruchy was sentenced to a maximum 28 years in jail for the murder of his mother Jennifer, 41, sister Sarah, 13 and brother Adrian, 15 at their home in Albion Park.
Just 18 years of age at the time, De Gruchy attacked his mother and sister in their beds and his brother in the garage.
His brother was found with 21 wounds to his face and neck and had been doused in petrol. His mother's injuries were so severe the coroner required the use of blood-match samples to be able to identify her body.
Three months after the murders, De Gruchy was arrested for the crimes but has long maintained his innocence, instead insisting he was with his girlfriend at her home during the time the killings took place.
Appearing via video link from Long Bail Jail, the Illawarra Mercury reported that De Gruchy sat emotionless as the court's proceedings took place.
De Gruchy has been forbidden from entering the Illawarra or Shoalhaven Local Government areas and is not to contact, stalk, harass or intimidate any of the family members of his victims. He is only permitted to contact his father, Wayne, who has indicated he will help his son upon his release.
Speaking to news.com.au, one of the policewomen who saw the murder scene has said De Gruchy should never be released. 'He is a sociopath, Belinda Neil added.