The bodies of five found inside a family home in Yeongam, South Jeolla Province, on Friday, are believed to be those of a man in his 50s who killed his wife and three sons in their 20s before taking his own life by drinking poison, police said Sunday.

South Jeolla Police Agency said an initial autopsy showed the man, identified by his last name of Kim, died of poisoning, while his wife and three children died from stab wounds.

Police found one knife and a bottle of insecticide in a search of the family’s home.

Investigators said it is likely that Kim drank the pesticide after stabbing his family members to death. They will conduct an autopsy on Kim’s body to check for chemicals.

To retrieve more evidence, the police conducted a second round of forensic examinations on Saturday. During the examination, the police found no signs of intrusion and that the house door had been locked. They plan to retrieve surveillance camera footage near the family’s home and conduct additional questioning. No suicide note was found.

The five bodies of the family members were found in the house by a neighbor who saw blood stains on the window. When the police arrived on site, Kim and his wife were found in the living room and his three children were found in the bedroom. His three children also had disabilities that classified them as "severely disabled" here -- including physical disabilities and autism -- according to the police.

The man had been recently booked by the police for allegedly sexually assaulting a woman in a nearby village on Sept. 4. He reportedly refused a summons by the police on Wednesday, two days before the police discovered his and his family members' bodies.