It doesn't take a crime scene investigator to see that Marg Helgenberger has one rock hard bikini bod.

The actress, her son and some friends were snapped on the beach in  St. Barts Sunday, and Breaking Celebrity News has the pictures.

At 52, the CSI star is giving Demi Moore a run for her money in the best bikini bod department.

Helgenberger ended her 20-year-marriage to actor Alan Rosenberg late in 2009.  They have a son, Hugh, 20, who was with his mom in St. Barts.