Wiktionary
vb. (context idiomatic English) To make something unclear and difficult to understand.
Usage examples of "muddy the waters".
They change license plates with another car of the same model and color as the stolen car to muddy the waters.
Clement could have been the one responsible for placing the voodoo doll outside the chief marshal's office, in an attempt to muddy the waters and throw a false trail into any investigation of Douglas Ramsey's murder.
Trying to lay the groundwork of a potentially big case without committing any of the procedural fuckups that would muddy the waters later on, for a third.
The whole Mob-hate thing serves to muddy the waters and gets him thinking that it's too big to mess with.
The information and advice from a dead man did little more than muddy the waters.
If Maria, friend and therapist, was already worrying about Glen's motivations, it would only muddy the waters further if Anne were to voice her growing suspicion that Glen, deep in a hidden place within that smooth, whole, and completely unscarred skin of his, held a certain dark fascination with the scars and injuries that his job had inflicted on her body and mind.
According to Andy, one of the gunslingers was actually a woman, but Callahan saw no need to muddy the waters further (although an impish part of him wanted to, just the same).