Mary says she will never give up the fight to get justice for her sister, Rebecca Zahau, who she claims was murdered. Although an investigation concluded Zahau died by suicide, Mary says her sister would have never taken her own life, especially not by hanging herself naked, as her body was found.

TELL DR. PHIL YOUR STORY: Are you involved in a story that has made the headlines?

In an exclusive interview with Dr. Phil airing Tuesday, Mary describes her sister as she remembers her.

WATCH: What Rebecca Zahau’s Family Claims Happened To Her The Day She Died 

“Rebecca has this aura around her. She can smile at you, and it makes you feel like everything’s going to be OK. She has a very positive influence on anybody around her,” Mary says. “I miss her a lot.”

This episode airs Tuesday. Watch more here.

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Why Forensic Pathologist Says Investigation Into Rebecca Zahau’s Death Needs To Be Re-Opened