The force received a report on Saturday morning that a boy fell unconscious in a flat of the Mansion. Officers rushed to the scene only to find the boy dead and arrested a 56-year-old man, whose nationality was confirmed as the Bahamas.

Officers further checked the surveillance video clips and noticed the deceased had entered the flat on the same day at 3 am with the arrestee and another teenager, who had left the scene at around 6 am.

After a preliminary investigation, police located the 15-year-old local boy in a residential flat in Ngau Tau Kok at 8 pm on Sunday. 

Police subdued the boy during a raid, seizing 720 grams of cocaine valued at around HK$700,000 and a haul of materials that were believed to be used for smoking drugs. 

The boy's father, 47, was later intercepted and arrested earlier this morning. 

"The deceased was born and raised in Hong Kong and was believed to be a friend of the 15-year-old arrestee," said Superintendent Alan Chung of the Kowloon West regional crime unit.

He added the two arrestees - the boy and the 56-year-old - had taken drugs with the deceased at Chungking Mansion.

The trio of arrestees was now in custody over an allegation of "trafficking dangerous drugs", with further investigation of the case ongoing by the police.