A Waltham man charged with raping a six-year-old boy is being held on $500,000 bail on Cape Cod .

Police allege that 40-year-old John Cox assaulted the boy in a Hyannis hotel swimming pool locker room over a year ago.

Cox was arrested last Friday on a child rape charge after the Massachusetts State Police Crime Lab matched forensic evidence at the Hyannis crime scene to his DNA.

He pleaded not guilty today during an arraignment in Barnstable District Court.

Cox is a Level 3 sex offender, considered the most likely to re-offend. he has two prior convictions.

The alleged rape occurred the morning of May 6th, 2006, when a Connecticut boy staying at the hotel was using the locker room.

Police say Cox was not a guest at the hotel. The alleged victim gave police a description of his assailant.