Honestly, the mom is at fault. And she is trying to push the blame to CNB using nice written letter etc.
Usually if the offender was caught drug trafficking, CNB will do a urine test to see if he consume drugs too. But her son was allowed bail the very next day means her son was tested not consuming drugs atleast 1week prior. If he was tested a drugs user, he will immediately send to de-tox centre.
From this, i assume her son is a not a regular drug user, and depression was a common side effect of not taking LSD. The mom should closely monitor her son situation and do "house imprisonment" and cut off any contacts of her sons frds etc. (confiscate the phones, lock the room door etc) Due to the emotional stress of awaiting the sentence, her son most likely order drugs from his sources or retrieve from his hidden stash in the house. As he is not a regular drug user, once he took the drugs, he will be too high to realise what he is doing, thus failing from high floors.
It is actually quite common for drug users to fall from high floors after taking the drugs. There are few cases the past few yrs. I vaguely remembered another case is a young gal fall from room window. Initially thou she committed suicide but After investigation found she took drugs, and the family was shocked cos she was those quiet quiet type