General Mansour al-Turki, the Saudi interior ministry spokesman said that the duo were suspects in the killing.
According to reports, the only thing being confirmed is that the twins follow Takfiri ideology, using a phrase which Saudi authorities use to refer to Islamic militancy. The spokesman declined to give further details as the case is still under investigation
It is still not confirmed that the alleged killing was influenced by Islamic State or religious ideology - or what the mother actually said as there was no contact with the 20-year-old twins, or their lawyers or family members.
It was confirmed by the interior ministry that the twins, Khaled and Saleh al-Oraini, were arrested on suspicion of stabbing their 67-year-old mother Haila, 73-year-old father and 22-year-old brother at the family home in the capital Riyadh.
Saudi media reported that the mother who died of her wounds, had disapproved her sons joining the Islamic State Jihadists in Syria.
The media said, that the supposed attackers were arrested while trying to abscond through the border to Yemen.
The online Saudi news website akhbaar24 reported on June 26 that this is the fifth killing killing incident of family members by suspected militants in Saudi Arabia since July last year.
According to previous reports there have been similar cases of other stabbing the close relatives by Islamic state members, including a massively reported incident in January in which a suspected militant killed his mother in public in the Syrian city of Raqqa because she had forced him to leave the group.