It refers to the mindset of the killer
ex·e·cute
verb
past tense: executed; past participle: executed
1.
carry out or put into effect (a plan, order, or course of action).
“the corporation executed a series of financial deals”
synonyms: carry out, accomplish, bring off/about, achieve, complete, engineer, conduct;
carry out (a judicial sentence, the terms of a will, or other order).
“police executed a search warrant”
Computing
carry out an instruction or program.
2.
carry out a sentence of death on (a legally condemned person).
“he was convicted of treason and executed”
synonyms: put to death, kill;
Yes, clumsily.