Cold case
01
悬案, 冷案
a criminal investigation that has remained unsolved for a significant period and lacks recent investigative leads
例子
The detective was assigned to the cold case unit, focusing on unsolved crimes that had gone inactive for years.
这名侦探被分配到冷案部门，专注于多年未破的悬案。
Advances in DNA technology have recently helped solve many cold cases that were previously considered unsolvable.
DNA技术的进步最近帮助解决了许多以前被认为无法解决的悬案。
