Princess Kamariah Sultan Abu Bakar, sister of the Sultan of Pahang, was stabbed to death and her partially-paralysed husband seriously injured when their son attacked them under the influence of drugs.
The royal couple's 21-year-old son died a few hours later apparently due to drug overdose, local media reports said on Tuesday.
The 64-year-old princess was slashed with a hunting knife by her son, Rizal Shahzan, at their home in Kuantan province on Monday after she tried to stop him from attacking her partially-paralysed husband, Ismail Tunku Sulaiman. He suffered wounds on the abdomen, the reports said.
According to neighbours of the princess, Rizal, in a deranged state, grabbed a screwdriver to stab his father when the princess tried to stop him. The resultant scuffle led to the son grabbing a hunting knife and slashing his mother's neck before attacking his father, the New Straits Times said.
The neighbours, who were alerted by the maid, tied up Rizal to a tree and informed the police. He succumbed to an apparent drug overdose a few hours later at the hospital, the paper said, adding that Rizal had a history of drug abuse.