Catherine Kieu, 50, faces felony charges of torture and aggravated mayhem.
Prosecutors alleged she drugged her husband, tied him up as he slept, cut off his penis, then threw it down a garbage disposal, the Los Angeles Times reported Thursday.
In their opening arguments Wednesday, defense attorneys said her husband was a sexual brute who forced Kieu to have sex with him, KTLA-TV, Los Angeles reported. The attorneys said Kieu's mother died when Kieu was a child and alleged their client was raped when she was 6 years old.
Kieu was arrested July 11, 2011, after she and her 60-year-old husband, who KTLA said was identified as "Glen B," had argued about a friend possibly staying at their house at a later date, prosecutors told the jury in their opening arguments.
After lacing his meal with a sleep aid, Kieu allegedly tied him to a bed. When he awoke, prosecutors said, she pulled down his pants, held his penis and cut it off with a knife.
She allegedly threw it in the garbage disposal and turned the disposal on, prosecutors said.
Emergency surgery to reattach the mutilated organ was unsuccessful.
Investigators said they believe Kieu was upset because her husband filed for divorce after 16 months of marriage, KTLA reported.
Police told the Times after the arrest that Kieu, who pleaded not guilty, had told officers her husband "deserved it."