The fitness guru who helped Matthew Mcconaughey and Jennifer Lopez shape-up has been caught up in a bizarre police investigation after a man was stabbed at his Hollywood home. Personal trainer-to-the-stars GUNNAR PETERSON wasn't home when 23-year-old NICHOLAS MARINO was attacked by a security guard. Sources tell news website Marino was once romantically involved with Peterson's estranged wife, JANET CROWN PETERSON, and took their break-up badly. Janet and her estranged husband obtained a restraining order against Marino, but the 23 year old wouldn't stay away. When he came too close for comfort on Wednesday night (06DEC06), he was attacked by a security guard, stabbed and then taken to a Los Angeles hospital, where he was arrested for making criminal threats, stalking and burglary. He is currently in intensive care.