muddy the waters

muddy the waters (muddy the issue) – наводить тень на плетень.

Meaning: confuse a situation more complicated or confusing than it was before by bringing in issues aside from those under discussion; make a situation less easy to understand or deal with.

Example: The investigation into the [scam] has not answered any questions. It has just muddied the waters.

see also
[наводить тень на плетень],
Сf.:
[fish in troubled waters]
see [ловить рыбку в мутной воде]
[мутить воду]