“Moreover, the Martins refuse to allow their son’s phone records to be released”
Really? Seeing as the world is upside-down, and Zimmerman has to prove his innocence...shouldn’t he be able to get the records?
If I were the prosecution I would argue the following:
Zimmerman's own testimony is that to his knowledge he never saw Martin before in his life, therefore the only information about Martin relevant to his defense is what Martin said and did in Zimmerman's presence that night.
Therefore, whether Martin called a drugdealer or did something else questionable or illegal using his phone prior to the encounter with Zimmerman is immaterial to Zimmerman's defense.
A defense attorney can make arguments against this, but it is up to the judge.