Just a theory -
I’m wondering if LE, more than two years later, lost track of a way to contact the witness who gave that tip three days after the murder, who assisted in the newly released sketch at that time.
But if that witness happened to state they were parked from noon to 5pm at the old CPS/DCS Welfare building, then LE asking anyone to come forward with information about the parked car was a round-about way to seek contact with this person once again.
And they did, which is why the parked vehicle has never been mentioned again. JMO
ETA - This transcript on the link below is somewhat jumbled but that’s also the only inference I can think of for this -
“the person apparently gave the investigating officers the information they were looking for ... “
ISP on Delphi killer: 'Somebody may have already interviewed him'