James Jimenez is facing 15 years behind bars for his alleged part in the burglary of Dunst's hotel room in 2007.
He is accused of joining Jarrod Beinerman in a raid on the star's suite at New York's SoHo Grand, stealing a number of items belonging to the actress and her then co-star Simon Pegg.
Beinerman, 34, was sentenced to four and a half years in jail last September (08) after confessing to illegally entering the suite and taking the Interview With A Vampire star's designer bag.
But Jimenez insists he believed Beinerman was collecting the bag for a pal's sick mother, and he merely tagged along on the errand.
He took to the stand at the State Supreme Court in Manhattan on Friday (25Sep09), telling Assistant District Attorney Tricia Stolfi, "I was just following him."
Items stolen in the raid include a $13,000 (£7,340) Marc Jacobs purse, $2,500 (£1,410) in cash, a cell phone, and a Balenciaga bag.
The trial continues.