bù liǎo liǎo zhī
不了了之
settle a matter by leaving it unfinished; not tie up loose ends; to end up with nothing definite
Example:
此案因证据不足, 最后不了了之。
Cǐ àn yīn zhèngjù bùzú, zuìhòu bùliǎoliǎozhī.
Prosecution of the case fizzled out for lack of conclusive evidence.