Police say Rothacher went to the woman's house to watch a movie late Friday. He had been drinking, according to documents filed in court.
He pushed the woman down on a bed and demanded sex, according to the documents. When she did not comply, he punched her in the stomach and said he would kill the unborn child. He also stabbed the bed with a knife "telling her that he didn't want to have to cut her," according to the charging document. He kept the knife in his hand while he raped her.
Police Lt. Dave Parker said he was unsure who the father of the baby is but said the woman has a husband.
The victim was sexually assaulted repeatedly, police say. She went to a local hospital's emergency room, where staff called police.
Rothacher was arrested Saturday. He was charged with four counts of rape and one count of third-degree assault.
Rothacher told police he didn't see the victim that night, that he went to the movies with friends instead.
On Wednesday, Anchorage Jail officials said Rothacher was still in custody. His bail is set at $50,000 cash.
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