Maureen Stratton is the sister of author and Oak Park native Michelle McNamara who wrote "I'll Be Gone in The Dark: One Woman's Obsessive Search for the Golden State Killer."
It was a name McNamara penned for the man who wrecked havoc in California for a decade.
McNamara died unexpectedly in her sleep in 2016.
“Bittersweet, is definitely what we are all feeling,” Stratton said.
Stratton, a law professor at Northwestern University, is helping her loved ones carry her sister's work forward.
“She was so committed to finding out who this was for the victims and the families of the victims," Stratton said. "That was really her motivation."
While the family was at an event for McNamara's book, just hours later, 72-year-old Joseph James DeAngelo was taken into custody.
DeAngelo is suspected of being the man known as the golden state killer who murdered 13 people and raped nearly 50 women during the 1970s and 80s.
“We just burst into tears because it was so, like, you know," Stratton said. "It was just so emotional that this had finally been solved, but also very sad that she was not with us to celebrate."
DNA evidence led investigators to DeAngelo, they said, who is a former police officer.
That's something McNamara wrote about.
“She also worked very closely with a lot of the police officers and investigators on the case too," Stratton said. "So, I think they spent a lot of time sharing theories themselves."
HBO has now picked up the rights to the book and will create a docuseries.
“We are, the whole family, is just so proud of her and not surprised because really, she was a force of nature and an amazing person and we miss her,” Stratton said.