Sao Paulo: In a distressing incident, a 16-year-old boy allegedly killed his parents and sister and stayed with their corpses at their family home for four days in Sao Paulo in Brazil, police said. According to media reports, the teen was upset over having his cell phone taken away.

The triple murder took place on Friday in Sao Paulo. The matter came to light on Monday after the boy called police and confessed to the crime. The teen remained inside the house with the bodies from Friday until early Monday, when he was arrested. 

Police investigation revealed that the teen was an adopted child who got "very frustrated" after his parents took his phone away following an argument. During investigation, the boy revealed that he shot his father in the back using his service gun. The 57-yearl-old deceased man was a municipal policeman.

Police said he then went upstairs and shot his 16-year-old sister in the face. His mother was not present inside the house when he killed the father-daughter duo. The woman (50) was shot dead by the teen when she arrived at the house.

Police suspect that the boy took the extreme step due to some sort of psychological disturbance. Police are also probing whether someone else was involved in the murder or whether the boy contacted anyone else on the phone.

During the four day period, the minor accused went to the gym and bought something from a bakery. Police said the minor, who was still angry, stabbed his mother's corpse with a knife.

The boy, who has been held at a juvenile detention center, maintained a "cold" demeanor when discussing the crimes, police said. Minor defendants are protected by special legislation in Brazil and cannot be tried as adults.