DENVER -- A woman accused of hiring a hit man to kill her ex-husband in Arizona has lost a legal battle over recorded telephone conversations implicating her in the death.

The 10th U.S. Circuit Court of Appeals ruled against 52-year-old Pamela Phillips who argued that recordings made by the alleged hit man as they purportedly discussed payment were improperly used by law enforcement to obtain a search warrant. The appellate court on Friday sent the case back to U.S. District Court, which originally heard her case.

Ronald Young is scheduled to go on trial in Arizona next month on a murder charge. Young and Phillips are charged in the 1996 death of Gary Triano, a real estate broker and developer whose car exploded at a country club.

Triano died after playing a round of golf on his 53rd birthday. Friends were waiting to take him to a surprise birthday party when they learned he had been killed.

Arizona authorities alleged that Phillips moved to Aspen after the divorce and then paid her lover $400,000 to kill her ex-husband. Authorities said she wanted to collect a $2 million life insurance policy left for their two children, but held by Phillips, until the children turned 18.

In 2006, federal authorities executed a search warrant at Phillips' Aspen home. Authorities later released the affidavit, which they said chronicled the relationship between Phillips and Young. Recorded conversations included threats, blackmail, money drops, a secret romance, and evidence of conspiracy in the 1996 slaying, according to investigators.

Police said Young, 66, was the man who placed the pipe bomb in a canvas bag and put it on the passenger seat of the Lincoln Town Car that Triano was driving when he was killed in Arizona.

Although Phillips and Young were "persons of interest" in the slaying, no arrests were made until October 2008, when Young was apprehended in Yorba Linda, Calif., after an Arizona grand jury issued an indictment on charges of conspiracy to commit first-degree murder and first-degree murder.

Young pleaded not guilty to charges of first-degree murder and conspiracy to commit first-degree murder.

Phillips is facing charges of first-degree murder and conspiracy to commit first-degree murder. She was arrested in December at a hotel in Vienna.