The FBI investigated whether Anna Nicole Smith was part of a plot to kill her tycoon husband's son, whom she was battling for his late dad's fortune, but prosecutors ultimately decided there wasn't enough evidence to charge the model who died in 2007 from a drug overdose, newly released files show.

Smith's FBI records, obtained exclusively by The Associated Press, say the agency investigated Smith in 2000 and 2001 in a murder-for-hire plot targeting E. Pierce Marshall, who was at the center of a long legal fight to keep the starlet, model and stripper from collecting his father's oil wealth, valued in the hundreds of millions. The younger Marshall has since died.