A 29-year-old Kapaa man whom law enforcement officials called "the Facebook stalker" has been sentenced to 10 years in prison for sexual assault and extortion after he lured two women via social media with the promise of modeling contracts.

Kauai Circuit Judge Kathleen Wata­nabe sentenced Leonard Alpeche Jr. on Wednesday to two five-year prison terms, to be served consecutively.

Alpeche was charged with multiple counts of third-degree sexual assault and second-degree extortion involving a 21-year-old woman and a 17-year-old girl on Kauai. He also was ordered to register as a sex offender, undergo sex offender treatment and pay more than $5,000 to the family of the minor.

First Deputy Prosecutor Jake Dela­plane said, "Alpeche is dangerously intelligent. He’s a perfect example of a new breed of sexual predators using his technological savvy to lure young women into these types of situations and do it for money and sex."

Since his January 2011 arrest, Alpeche has been incarcerated at the Kauai Community Correctional Center in lieu of $425,000 bail. In May he pleaded guilty to the charges under a plea agreement.

Delaplane said the plea agreement was made "so the victims wouldn’t have to relive the horror by testifying in trial."

Alpeche used Facebook and other social networking sites to stalk, extort and later sexually assault young female victims, the prosecutor’s office said in a news release. Dela­plane said Alpeche created a Facebook account to pose as a 15-year-old girl, and sent messages to girls he targeted in which he claimed to be a model for a fictitious modeling agency on Kauai that catered to North Shore residents.

He encouraged girls to sign up for lucrative modeling contracts that were bogus and provided an email address and phone number, the prosecutor’s office said. Alpeche would then use a series of email addresses, phone numbers and Internet messaging services in which he masqueraded as a secretary, agent and a photographer of the fictitious modeling agency.

He requested bikini, seminude and nude photos for the girls to "audition" for the fake contracts, according to the prosecutor’s office. After he received the photos, Alpeche would demand to meet the women in person and threatened to release the photos if they did not have sex with him, the prosecutor’s office said.

Delaplane said Alpeche described himself as a modeling agent and persuaded the 21-year-old woman from Kauai to send nude and seminude photos of herself, the prosecutor’s office said. After he received the photos, Alpeche coerced her to meet him at the Lihue Ballpark Complex. He threatened to release the revealing photos to her friends, family members and employers if she failed to comply.

The woman met Alpeche at the ballpark late one night in October 2010. Dela­plane said Alpeche wore a mask and a hood to conceal his identity and motioned her to go to the park bathroom. Alpeche told the woman he was a victim himself and that the people she contacted were part of an organized crime syndicate that would harm him and his young son if he did not provide them with photos of himself and the victim engaging in sex acts.

The victim called police after the assault. Alpeche was arrested and charged with multiple counts of sex assault and extortion after law enforcement conducted an extensive investigation to catch the predator.

After Alpeche was charged in the case involving the 21-year-old woman, the FBI contacted Kauai police and the prosecutor’s office concerning a similar case in which the 17-year-old local girl was assaulted.

Alpeche met the minor five times between December 2010 and early January 2011 after he threatened to release revealing photos if she didn’t provide money and engage in sex, the prosecutor’s office said. He would tell her to meet him at a park, behind public buildings and dark alleyways and wore a hoodie to hide his identity. Alpeche extorted more than $7,500 from the 17-year-old girl.

"It’s unfortunate that there are evil people out there that use technology to victimize humanity," said Internet crime expert Chris Duque, a retired Hono­lulu Police Department detective who specialized in cybercrime investigations.

He investigated a similar case involving "sextortion" that occurred in 2003 while he was a detective with the Criminal Investigation Division.

Duque said a person can never trust communication via the Internet, email or cellphone because an individual doesn’t know for sure with whom they are communicating. The message could be from a predator who is using someone else’s cellphone, email address or social media Web page.

FBI Special Agent Tom Simon said, "It’s important for parents to keep a finger on the pulse of their children’s social media interactions. When adults see that a sexual predator has been taking advantage of Hawaii’s youth, we encourage them to contact law enforcement immediately."