(NEXSTAR) – A 21-year-old man is accused of sexually assaulting a 12-year-old girl repeatedly after moving into her room for a month – hiding under the bed and in the closet so her grandfather wouldn’t find him, prosecutors say.

Zacharias Adrian Cavasos was charged in U.S. District Court in Portland with sexual abuse of a minor, The Oregonian reports.

Cavasos, who allegedly traveled from Washington state to the girl’s family home on the Umatilla Indian Reservation in Oregon, met her via social media in December.

Prosecutors say Cavasos used Snapchat, Facebook, Instagram and texts to message the girl, ultimately convincing her in early February to meet him at the Wildhorse Resort and Casino.

Cavasos allegedly slipped into her room on Feb. 10 and stayed there undetected for two weeks.

Assistant U.S. Attorney Jennifer Martin said Cavasos took slats out from under the girl’s bed so he could hide beneath it, according to the paper.

Prosecutors say her grandfather saw him on Feb. 25 and ordered him to leave, but Cavasos returned later and hid out until March 11.

“I’m troubled by the allegation that despite knowing the victim’s age and the fact that he was not to return to that residence, he went back and further allegedly engaged in the same criminal conduct,” Judge Youlee Yim You said Wednesday. “When I started reading the nature of the allegations, I really was quite surprised by what I read, I have never been aware of anyone alleged to have been living in a 12-year-old’s bedroom for a month.”

Cavasos later admitted to investigators that he had sex with the 12-year-old on multiple occasions, court documents say.

The 21-year-old’s attorney argued that his client may have an intellectual disability and has no prior convictions.

Multnomah County Sheriff’s Office records show he was booked March 13 and released Thursday afternoon.

Judge You ruled Cavasos could await his trial at a clean-and-sober facility.