The possibility that a 15-year-old girl found dead at sea was drugged before her death could not be ruled out, despite a lack of evidence supporting this, a Hong Kong government chemist told an inquest on Monday. Hong Yau-hin told the Coroner’s Court no toxic substances were detected in the body of Chan Yin-lam, whose cause of death remains unclear after she was found in the waters off Tseung Kwan O on September 22 last year. The college student was said to have behaved strangely on September 19, the day she was last seen by friends and caught on security cameras. New campus video of teen found dead at sea shows she left shoes behind The forensic scientist was called to testify for the second time in the court inquiry into Chan’s death, as the five-member jury looked into whether the teen had been knocked out by chloroform or other anaesthetics before she entered the water. Hong said that while no such chemicals were found in Chan’s body fluid samples, that did not necessarily mean the teen had not been dosed with chloroform, because a considerable time had passed when her body was discovered. “The lab finding does not mean [chloroform] had not been used. Chloroform, in its gas form, can be lost readily, especially when the body is in a decomposed state. It’s no surprise if the substance had been lost,” Hong said. The only thing that could be concluded from the forensic examination was that if chloroform had been used, it was not a lethal dose, Hong added. Cause of death of teen found at sea unclear, but drowning a possibility: experts On September 19, Chan reportedly slept on a classroom floor using her classmate’s school bag as a pillow, spent half an hour clearing her locker, sat on the floor of a train carriage after she left school with friends, and later returned that evening to wander the campus for no apparent reason, leaving her personal belongings behind in the process. Forensic psychiatrist Robyn Ho Mei-yee earlier suggested to the court that such odd behaviour might be symptoms of a psychotic episode , which could be induced by cannabis use. Chan’s social worker, Vivian Tong, testified Chan tried cannabis once on August 11, but she was unsure whether the girl had taken the drug on other occasions. Hong said on Monday that Chan’s body tested negative for cannabis, meaning she had not abused the substance within five days before her death. Chan’s mother, Ho Pui-yee, was absent at Monday’s hearing after being invited to give a closing speech to the jury. Magistrate Ko Wai-hung will direct the jury on Friday, before a verdict is reached.