Justin Bieber: Brat Packer?

Can't imagine 'tween heartthrob Justin Bieber acting like a brat? Well, never say never. According to veteran CSI actress Marg Helgenberger, the 17-year-old was guilty of acting like a big baby when he did a two-part guest stint on the hit CBS drama. The 52-year-old actress rolled over on the Biebs in a radio interview for Europe 1 that was also taped in front of a live audience. Helgenberger told the interviewer that Bieber acted like it was his world 2.0 on the set of the popular crime show. Helgenberger reveals, "I shouldn't be saying this, but he was kind of a brat. He was very nice to me. But he locked one of the producers in a closet and he put his fist through a cake that was on the cast's table." While she didn't exactly sing Bieber's praises for his acting prowess, she also didn't take him to task for a lack of acting chops. When asked whether his guest appearance was a ratings ploy or a casting because he's "truly a good actor," Helgenberger replied, "Justin Bieber wasn't bad bad. But he'd never acted before . . . He's better than you'd think." Bieber appeared on two episodes which aired in February. His homicidal character apparently had a fitting demise when he was killed by police. Apparently, Bieber didn't appreciate Helgenberger's verbal lashing as he Tweeted, "it's kinda lame when someone you met briefly and never worked with comments on you. I will continue to wish them luck and be kind." He added, "I know who i am and sometimes people r just going 2 say what they want. Keep ur head up and be the man ur mama raised. "