SINGAPORE - An internal investigation by the Central Narcotics Bureau (CNB) is under way following the death of a 17-year-old boy after he was arrested by its officers.

Justin Lee, who had been charged with drug trafficking on June 24, died on Sept 16 from a fall from height.

His mother, Ms Cecilia Ow, 51, on Tuesday (Oct 12) posted a letter addressed to Minister for Law and Home Affairs K. Shanmugam on her Instagram page, describing her son's experience of being arrested and his history with depression.

The CNB said on its Facebook on Wednesday: "Some statements have been made publicly about how Justin was arrested and questioned. CNB has been investigating the circumstances of his arrest."

The bureau added that the investigations are expected to be completed before the end of the month, and the Ministry of Home Affairs (MHA) will make the findings public.

"The allegations are being fully investigated," it said, adding that MHA will also take further steps if necessary.

CNB said it arrested Justin after it conducted investigations into a person who was suspected of trafficking a Class A controlled drug online. Drugs in this category include heroin and LSD.

Outlining some of the details of her son's arrest on Feb 3, Ms Ow, a senior lecturer at a polytechnic, told The Straits Times on Wednesday that she was not able to speak to her son, even while officers searched his room with him at their home in Serangoon North.

She spoke to him only when she bailed him out on Feb 4 night.

In her letter to Mr Shanmugam on Oct 1, she referenced the case of Benjamin Lim, 14, whose death was rule a suicide after he was found dead at the foot of his block in Yishun in January 2016.

He had been questioned at Ang Mo Kio police division hours earlier for the alleged molestation of an 11-year-old girl in a lift.

Ms Ow told ST: "Things really need to change."

She called for a separate u...