It is not likely that classmates/roommates poisoning one another. Could this cold case be a lover's quarrel caused poisoning? If you review all the poisoning cases in the world, you will find majority of the time, the lover/spouse is the #1 suspect and correctly so. I don't know why lovers always want to kill each other but they have the strongest motive and best opportunities. Did the victim herself got involve romantically with someone else? And when the victim wants to end the relationship or decided to date others, her lover got jealous and trying to poison her...? It's hard to believe a classmate/roomate has the motive strong enough to kill each other, a bad prank maybe but not killing.
Since this is a cold case, I think one of the feasible ways is to talk to the attending doctor who was treating the victim at that time in 北京協和醫院 and they may offer some clues. I think that's the better way to approach this. And I think investigative journalism needs be encouraged as an independent 3rd party because it seems to me there's a lack of the effort from official investigational authorities according to the report. Because it seems odd to me for 北京協和醫院 to behave in the way they did back then regarding how to diagnose and treat the victim.
According to wikipedia, (https://zh.wikipedia.org/zh-hans/朱令鉈中毒事件)"國家教委辦公廳發布《關於加強學校實驗室化學危險品管理工作的通知》（教備廳（1997）13號），指出：“1995年5月，1997年5月，清華大學、北京大學先後發生兩起學生鉈鹽中毒案件。除涉嫌人為作案外，鉈鹽未按劇毒品管理是其重要原因。” It seems the other poisoning case in Peking U in 1995, one year after the victim, is because 王小龍 thought 江林 is leaving him... Another seemingly lover's poisoning case.
