As Jason Bassford says, choice of tense between past and present perfect is often just individual preference or whim, especially since the meaning of the two tenses is so similar.
I doubt it was thought out with as much care as a great novelist would take, but by the choice he made, the author reveals how he understands the nuances of the two tenses.
The first verb, in the present perfect implies the action is in some way still ongoing:
"If this murder was intended to hurt me, it has succeeded." I.e. It has succeeded and is still succeeding, meaning "I am still hurt".
The second verb, using the simple past tense, indicates an action that is completely finished:
"If it was meant to send a message, it failed." It failed to send the message, and that's the end of it.
Maybe I am splitting hairs here, but I think it is an illustration of the subtle difference between simple past and present perfect.