Joseph M. Rivera accused of filming sex assaults on unconscious women

Joseph Rivera is in detention in Las Vegas. Photo: Las Vegas Metro Police Department

A disc jockey who once lived and worked in Alexandria was being charged with rape and other sexual offenses after he allegedly filmed videos of himself assaulting and having sex with unconscious women.

Joseph M. Rivera, 34, was arrested in Las Vegas following an investigation by Fairfax County and Alexandria Police.

“This individual would have access to many, many women over the past years because of his job,” says Lucy Caldwell, Fairfax County Police spokeswoman.

A few of the videos were filmed in Rivera's Lorton home. During an interview with authorities, Rivera admitted to making the videos between November of 2011 and December of 2012.

"I was shocked and everyone was as well," says Rivera's former roommate, who asked not to be identified.

"I would think anyone would call the police if you know what was going on," he says. "Once I found out what was going on... I let the police know."

Only some of the victims have been identified, but others that appear in the videos have not, police say. Most of the victims were in their twenties, the Washington Post reports, and police say many victims still don't know they were filmed.

"It's crazy," says James Foster. "You never know what to expect. You never know who's living amongst your neighborhood. I wouldn't have guessed."

Some victims have told police they did not give permission to engage in sexual acts with Rivera. Rivera's charges include rape, aggravated sexual battery and two counts of unlawful filming.

He's is currently being held in Las Vegas, pending extradition to Fairfax County.