Sheila Wysocki knows what it feels like to lose someone close to her and have the murder case go unsolved.
In 1984, her college roommate, 20-year-old Angie Samota, was raped in murdered. For more than two decades, her killer remained unknown.
But Wysocki would not let the case go. She hounded the Dallas Police Department for several years – calling them more than 750 times, she estimates – until recovered DNA evidence pointed to serial rapist Donald Bess, who was eventually convicted and sentenced to death for the crime in 2010.
“A private investigator once told me, ‘Yeah, some cases are not meant to be solved,’ ” Wysocki, now 53, tells PEOPLE. “I thought, ‘Oh, buddy, you are so wrong. I am going to solve this.’ ”
The tenacious mother of two earned her P.I. license during her investigation into Samota’s murder. But after the case was solved, she never thought she’d use it again. “I didn’t care about any case other than this one,” she says.
Wysocki’s plans changed, however, when the public heard about her efforts on Samota’s case. She was subsequently inundated with requests from strangers who had lost loved ones in cases that were still unsolved.
“There are thousands of unsolved murders,” Wysocki says. “And I thought maybe there would not be if authorities and victims’ families worked with each other.”
For more on Sheila Wysocki and her work on cold cases, pick up this week’s issue of PEOPLE on newsstands Friday.
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The Nashville-based P.I. has since dived back into investigative work, fueled largely by the all-too-familiar desperation and frustration of victims’ loved ones.
“I know what families go through to find answers,” she says.