It’s been more than a decade since Laci Peterson was senselessly murdered — but the passing of time never made it easier for Sharon Rocha, Laci’s mother. Sharon is speaking out as part of a new documentary chronicling the trial that led to Laci’s husband, Scott Peterson, being found guilty of first- and second-degree murder of his wife and unborn child, whom they planned to name Conner. In the first sneak peek at the documentary, Sharon details the last time she saw her daughter, who was only 27 when she was killed.

“She and I were sitting side-by-side and Scott was sitting on the floor, and we were watching TV and she said the baby was kicking, so I put my hand on her stomach, because I’d never felt him kick. I still didn’t feel him kick even when she said that,” Sharon says in the clip. “But she leaned over to me and she said, ‘Mom,’ she said, ‘Scott doesn’t like to do this.’ She said, ‘I’ve asked him about, you know, feel my stomach when the baby kicks, and he never wants to touch my stomach.’ That really, really bothered me. And that was the last time I saw her.”

As one can imagine, it was difficult for Sharon to learn that it was her own son-in-law — someone who, for years, she loved as family — was the one responsible for killing her daughter. “I mean, it’s not like this is a total stranger that you might be suspecting,” she tells the cameras for ABC’s Gone Girl. Truth & Lies: The Murder of Laci Peterson. “This is somebody that’s been a member of your family for several years now, and it’s really, you know, the back and forth and the guilt about feeling this way, and how it may have an effect on the relationship with my daughter if I’m wrong.”

She continues, “That’s the last person you want to think had anything to do with the disappearance of your daughter — her husband. The person that was a member of your family, somebody that you loved and cared about, and thought he felt the same way about your daughter. And knowing how she felt about him.”

Since Scott was sentenced to death in 2005, Sharon has mostly remained out of the spotlight — save for interviews about her daughter, and political reform that she’s been active with. In 2012, she explained that given her daughter’s Christmas Eve disappearance, the holidays mark an especially difficult time — but her many grandchildren make it a little easier. She explained at the time, “If it weren’t for the grandkids, though, I wouldn’t have a Christmas.”