SAN DIEGO -- A Rancho Penasquitos man who enlisted his adult stepdaughter to help him molest a girl and take nude photos of her over a period of several years is facing a dozen years in jail.

Rick Stockton, 51, was sentenced to 12 years in prison Tuesday and will have to register as a sex offender for the rest of his life.

He pleaded guilty June 11 to four counts of committing a lewd act on a child under 14 and admitted an allegation that the molestation involved substantial sexual contact.

Deputy District Attorney Mark Skeels told Judge Timothy Walsh that Stockton was also involved in grooming additional victims, including the girl's younger sister.

Skeels said Stockton betrayed the trust of the victim's family, neighbors who had grown fond of the defendant's family and let Stockton's daughter babysit their children.

The victim, who was about 11 when the molestation began in 2001, has undergone counseling for depression, and her social skills have been adversely affected, her father said.

Investigators said Stockton began photographing the girl in his home office. A search of his computer turned up nude photos of the girl, and he was arrested last November.

His 26-year-old stepdaughter, Lindsey Stockton, was also arrested late last year in Safford, Ariz., where she was working as an assistant editor at a newspaper after graduating from the University of Arizona with a journalism degree.

She pleaded guilty June 11 to one count of committing a lewd act on a child. She faces anywhere from probation to eight years in prison when she is sentenced Sept. 5.

An arrest warrant indicated Lindsey Stockton gave alcohol to the victim and encouraged her to participate in sexual acts with Rick Stockton. The stepdaughter also took nude photos of the victim, according to the arrest warrant.