"I don't think he has any right to do it," Cox said. "They're the private writings of a teenage girl."
Steve Powell last year posted a journal entry written by one of Susan's friends on his website, www.susanpowell.org.
The Cox family has criticized the Powells for their suggestions that a then 28-year-old Susan willingly left her two young sons, and for not doing more to help find her. Her husband, Josh Powell, has not spoken with West Valley City police detectives since the early days of his wife's disappearance. The Coxes have also criticized Josh Powell as an abusive and controlling husband.
Josh and Steve Powell, meanwhile, have said the Cox family has a history of mental illness and Susan's parents were emotionally abusive to her.
The Coxes have denied the claims about their family and called the Koecher theory another effort to take the focus away from Josh Powell as a suspect in his wife's disappearance.
Steve Powell said he emailed the FBI and U.S. Marshals about a month ago with information he wanted them to know, but on Thursday he declined to offer details. He said Josh Powell still has no plans to speak with West Valley City police because he is unhappy with how they treated him in the early days of the investigation.
"They burnt their bridge," Steve Powell said.
West Valley City police Sgt. Mike Powell, no relation to the Powell family, on Wednesday declined to comment on whether investigators had reviewed the journals. The case, he said, is still "an active investigation."
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