A Las Vegas man is under arrest accused of sexually assaulting his mentally challenged sister and attempting to offer her for sex out on the internet. 34-year-old Rodney Nickerson is being held on $800,000 bail.

According to a police report, Nickerson admitted to putting a photo of his 36-year-old sister on craigslist website. The ad featuring his sister apparently asked men if they wanted to have sex with her.

The report states Nickerson also fondled his sister and had another man touch her as well. Nickerson's mother told New's 3 her son has always taken care of his sister since they were little .

"I know my son didn't do what they said he did," Deborah Nickerson told News 3. "My son also stuck up for her, (has) taken care of her. He's never bothered her sexually."

Police say they received a tip about the craigslist ad around mid-March. An undercover officer tried to arrange a meeting with Nickerson twice, but Nickerson never showed up.

Nickerson goes before a judge to answer to these charges at the end of the month.