In this Oct. 25, 2012, file courtroom drawing, Federal Defender Julie Gatto requests bail for her client, New York City Police Officer Gilberto Valle,
In this Oct. 25, 2012, file courtroom drawing, Federal Defender Julie Gatto requests bail for her client, New York City Police Officer Gilberto Valle, right, at Manhattan Federal Court in New York. The New York City police officer accused of kidnapping conspiracy admits to thinking about abducting, cooking and devouring young women. His own lawyer has shown prospective jurors a kinky staged photo of a woman trussed up in a roasting pan to test their tolerance for the officer s "weird proclivities." (Elizabeth Williams/The Associated Press)

NEW YORK (AP) — The wife of a New York City police officer will testify at a federal trial to explain how she discovered that he was discussing kidnapping, killing and eating women.

A judge outlined the parameters of Kathleen Mangan's testimony against her husband, Gilberto Valle, whose trial was beginning Monday. Mangan can tell a jury about her discovery but not about the couple's confidential communications or about his mental condition, U.S. District Judge Paul G. Gardephe said.

Valle, 28, is charged with scheming to abduct, kill and eat dozens of women. His lawyers say he was only indulging in fetish fantasies. Opening statements at his federal trial are set for Monday afternoon.

Prosecutors said in court papers that Mangan fled their home on Sept. 10, 2012, believing he was planning to kidnap, rape, torture and murder her.

"Mangan also discovered that her husband had similarly heinous plans for women she knew and to whom she was close," the papers said.

Mangan gave her computer to the FBI, which found it "contained evidence of Valle's illegal plans," the government added.

The defense denied Mangan was a potential victim. Valle had made clear that his wife "was unavailable for any kidnapping fantasy and then chat participants discussed sexual fantasies concerning other women," the defense papers said.

Valle, a baby-faced tabloid sensation known as the "Cannibal Cop," is expected to take the stand to make the case that it was all harmless fantasy played out on Internet sites like darkfetishnet.com.

The defense also is planning to show jurors the videotaped testimony of darkfetishnet.com co-founder Sergey Merenkov in which he describes the site as a "social media network."

Merenkov called the site "a clone of Facebook, but it is oriented to people with fetishes that are not considered standard."

Asked the most popular fetishes, Merenkov responds, "All sorts of asphxiation" and "peril cannibalism."