No, but attempted murder, maybe. If a “reasonable man would reasonably believe” that the mannequin was actually a human, but, nevertheless, the accused smashed it with a hammer using both hands ...
Not even ...
A reasonable man...
...not reasonable & must prove beyond reasonable doubt
And the cops could now take that hammer into evidence. If it has blood from the murder victims on it, Schindler should be on his way to Old Sparky Old Jabby.