David Boreanaz David Boreanaz

Tonight's Bones bids farewell to a favorite baddie when a mysterious sniper takes out Gravedigger Heather Taffet. "She's on her way to court and gets her head blown off," says star David Boreanaz, who also directs the episode.

Seated next to the Gravedigger at the time of her execution is Sweets (John Francis Daley), who "is really shaken up by the whole thing," Boreanaz teases. "He thinks he's next." The incident also proves unnerving for Boreanaz's Booth when it's revealed that the sniper is someone from his past. "As we analyze the case, we figure out there's only one person who could have made this shot," he says.

That someone — Jacob Ripkin Broadsky (Arnold Vosloo) — is a man Booth once highly respected, but who has now gone to the other side. "It's going to be an interesting arc that will play out over a few episodes," says Boreanaz. "There's a lot of vulnerability going on, so I directed the actors to think, 'You could be the next person shot — or fired from this show.' That's the fear I wanted to plant in their heads to make it come across on screen."

Although the episode marked Boreanaz's third time behind the camera, it was his first crack at directing Ryan O'Neal, who returns as Max, the father of Emily Deschanel's Brennan. "Ryan knows what he's doing, so you just kind of understand what his mood is that day, tell him where the camera is and let him do his thing."

Bones airs Thursday at 9/8c on Fox.

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