NCIS: Los Angeles is back in production, and Callen and Deeks will both sport a different look in season 6.

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The series is busy filming episode 2, "Inelegant Heart," and new behind-the-scenes photos indicate that Callen's (Chris O'Donnell) buzz cut will be a thing of the past - at least temporarily.

Gone is the clean-shaven G, replaced instead by a bearded agent with a mop of dark hair that O'Donnell probably spent the entire summer growing (see photo here).

'NCIS: LA' Season 6 Filming Begins, Deeks Has Short Hair?

However, Callen won't keep this look for long. O'Donnell directed an untitled season 6 episode last spring, and Callen's short hair definitely made an appearance. While it is unknown why the special ops agent decided to switch up his look, there are two possible theories. There may be a long time jump between the premiere ("Deep Trouble: Part 2") and "Inelegant Heart," or there is a chance that Callen was injured during the premiere and grew out his hair while recovering.

Meanwhile, Deeks will break out a fake beard as he takes on his homeless Deeks (Eric Christian Olsen) persona. Complete with baggy clothes, a beanie, and a shopping cart, Olsen spent Tuesday undercover.

Find out more when NCIS: LA returns to CBS on Sept. 29 at 10 p.m. ET. Click the video below to see a preview for the series' latest episode, "Deep Trouble."