One key element is that he was a nurse, which gave him easy access to patients and drugs. Another is that he was able to move from one hospital to another, continuing his heinous acts undetected for a while. Also, the fact that he used poisoning as his method was significant.
Well, first of all, Cullen's employment in multiple hospitals is a major element. It meant that his crimes were spread out and not immediately obvious. His choice of poisoning as the means of killing was a key factor. It was a relatively quiet and hard - to - detect method. The fact that he targeted patients in a healthcare setting, where they were supposed to be safe, is also very important. And finally, the efforts of the law enforcement and the medical community to finally stop him and bring him to justice are key elements of this true story.
Chapter 332, "Chen Ying's New Discovery, Xia Yuning, and a String of Good News (Part 3)", is the clearest early answer because it turns Han Shuang's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Oh, I see, no wonder the captain had us bring iron picks and shovels... and follows through with Last month, when he returned from Beiyuan, he specially brought this....
Chapter 108, "Without accumulating virtue through words, calamities of bloodshed will only increase, not decrease.", is the clearest early answer because it turns Shining Transformation Trip's situation into a concrete plot event.
Chapter 333, "Silver Mine from the Heavens, Yu Yao and Yu Sheng, No Need to Use a Bull Knife to Kill a Chicken [10,000-Word Mega Chapter Continued]", is the clearest early answer because the violence around Xia Hong becomes final instead of hypothetical. Early on, A typical member of a low-level Hunting Team in the Earth-digging.... By the end, Eh, there are water beads, what is this?" Suddenly, a cool sensation....
Chapter 307, "I Am Sister's Real Younger Brother!", is the clearest early answer because it turns Sister's situation into a concrete plot event.
Chapter 334, "Hanqiong's Seven Divisions, Moao Mountain, Beishuo Revisited 5", is the clearest early answer because it turns Cold Beasts's situation into a concrete plot event. The chapter gives readers a real answer by opening on According to Fan Kui, let's first explore northward together to see... and ending on Does Beimang Mountain have even half its height?" Hearing Zhao Hu's....
Chapter 94, "Finally, Someone Comes to Calculate Affection!", is the clearest early answer because it turns Shu Yan's situation into a concrete plot event.
Chapter 405, "The Person Saved Casually Turns Out to Be a Diplomat?!", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event. It opens with The medical student was completely dumbfounded.
Chapter 203, "She's Not Her Maid!", is the clearest early answer because it turns Xiao Xu's situation into a concrete plot event. It opens with Ah Fu knew he might have made a mistake, and after glancing at Su... and closes on Su Yinwan's expression stiffened for a moment but then quickly....
Chapter 349, "Attempting to Cheat, East Ridge's Strength, Lu Yang's Tactics", is the clearest early answer because it turns Leader Lu's situation into a concrete plot event. The chapter gives readers a real answer by opening on The saying "Gaining ten thousand jins of silver is not as valuable as... and ending on Even if you escalate it to Dean Gu, we still can't deliver." "That's....
Chapter 27, "Signing Jiang Yan is fine, but you have to follow along too.", is the clearest early answer because it turns Signing Jiang Yan's situation into a concrete plot event. The chapter gives readers a real answer by opening on They had spent an entire year gradually inviting a few people.