Showtime just made the official announcement of Julia Stiles’ casting on Dexter following days of speculation. Here is a portion of the release, which includes details about the length of her stint and her character.

LOS ANGELES, CA June 7, 2010 – Julia Stiles has joined the cast of SHOWTIME’s Emmy-nominated drama series DEXTER. Stiles, who will appear in ten episodes in the upcoming fifth season, will play a mysterious young woman who forms a unique relationship with Dexter (Michael C. Hall) in the wake of the death of his wife. Production on season five begins this month and will premiere in the fall on SHOWTIME.