GREELEY, Colo. -- A Weld County district judge says prosecutors cannot use at trial a confession made by a man accused of killing a transgender woman in Greeley.

Judge Marcelo Kopcow issued a ruling Tuesday that threw out a July 30 confession to police by 31-year-old Allen Andrade of Thornton.

Andrade is accused of killing 18-year-old Angie Zapata, a transgender woman found dead July 17, 2008, in her southeast Greeley apartment. He faces a charge of first-degree murder after investigators said he beat Zapata to death with a fire extinguisher and then cleaned up the apartment before leaving.

Kopcow determined that statements Andrade made to investigators were elicited after Andrade clearly stated he was finished answering questions about 40 minutes into a two-hour interrogation.

His ruling also bars prosecutors from presenting evidence that Andrade is a gang member.

Kopcow also ruled that Andrade's recorded statements in telephone calls from the Weld County Jail could remain as part of the evidence against him. In those calls, Andrade allegedly told his girlfriend that he "snapped" and that "gay things need to die."

Andrade was arrested in Thornton on July 30, driving Zapata’s car.

Zapata was born as a male but was living as a woman. Prosecutors said Andrade beat her to death after discovering she was biologically male.