Arrest is made in rape of boy, 6

A Waltham man, whom police had been working to identify for more than a year, was arrested Friday for allegedly raping a 6-year-old boy in Hyannis.

Police arrested John Cox, 40, at his Waltham workplace and charged him with rape of a child with force.

Cox, a registered level-three sex offender, was previously convicted twice of raping children in other Massachusetts communities, according to Barnstable police.

The Sex Offender Registry Board designates level-three offenders as being a high risk to commit further offenses.

In May 2006, Cox allegedly sexually assaulted the 6-year-old, who was visiting from Connecticut, in the communal locker room at a Hyannis hotel, according to Barnstable police.

The boy, who was at the hotel with his family and used the swimming pool, told police about the assault. Cox was not registered at the hotel.

Cox was identified as a suspect after Barnstable and State Police collected forensic DNA evidence from the crime scene and verified the DNA source through a sex-offender database.

"If it wasn't for the DNA and this database, I don't know how well the case would have gone. I think it would have been a hard case to crack," said Barnstable police Sergeant Sean Sweeney.

"It shows you that the system does work," he said.

Cox's convictions were for the rape of a child with force in October 1997 and indecent assault on a child under 14 in October 2001. He will be arraigned tomorrow.