Final answer:
In 'The Office' S5E14, it is revealed that Meredith Palmer is the coworker who spent time in juvenile detention.
Step-by-step explanation:
In S5E14 "Lecture Circuit Part One" of the television show The Office, we find out that the coworker who previously did some time in juvenile detention is Meredith Palmer.
This is revealed through a series of her anecdotes and eventually a direct admission to one of her colleagues. Meredith's character is known for her brash and unapologetic behavior, and this revelation adds depth to her backstory in the series.