The Los Angeles Times dissects Stewart's quick trip from fame to infamy by tracking how the PDA photos ended up on the cover of Us Weekly.
Seems the shutterbug didn't recognize the "middle-aged man" who climbed into Kristen's Mini Cooper on July 17, but quickly sussed out something was up when they began "pawing each other like teenagers."
He called his agency -- FameFlynet -- for backup, and three more photogs were dispatched to trail Stewart and Sanders on their mobile make out session.
Later, while looking over the images they'd captured, the shutterbugs identified the mystery man as Sanders.
"That was when we realized, 'Oh, my God, she's not just cheating on Rob -- this guy is married and has kids,'" explains FameFlynet owner Scott Cosman. "It was pretty scandalous, and it had so many different angles to it."
In order to keep the story under wraps, the agency went directly to Us Weekly. One former employee of the mag estimates it paid around $250,000 for the shots.
"There was no question when we saw those pictures that this was going to be one of the biggest stories of the year -- if not the biggest," Dina Sansing, entertainment director at Us, tells the Times. "And I'm not sure the 'Twilight' fans would have believed the news without the undeniable photographic evidence."
Alas, some Twi-Hards stubbornly remain in denial, but most have accepted the cold, hard reality, including one of Stewart's most ardent fan sites, which closed up shop in the wake of the scandal.
The administrators of the site explained that they "just can't support and condone someone who would cause so much heartbreak not only to the person she loves but to another family as well. It would be hypocritical of us to continue posting here like everything is okay when in our hearts we don’t support her actions."