Here is the answer on whether or not NCIS will continue Abby’s brother’s story arc on season 10.
From TV Line: “Abby’s brother” storyline touched on early in Season 9. “I can tell you that we are far from done with Abby’s brother,” Glasberg assured. “That’s something we will definitely be touching on in Season 10.” And though the show boss was a tad less committal to the matter of McGee’s never-seen, estranged father, he did allow that that storyline “may very well be something we revisit, too.”
You can check NCIS season 10 news and spoilers HERE.