Mother of Woman Allegedly Killed by Boyfriend's Ex-Wife 'Worried for Her Safety Every Day'

Police say Chelsea Cook fatally shot Lisa Williams in front of her own twin children.

The mother of a woman who police say was fatally shot by her new boyfriend's ex-wife said she had been concerned for her daughter. 

Lisa Williams, 26, died on Nov. 25 after allegedly being shot multiple times by Chelsea Cook, 32, the ex-wife of her boyfriend Travis Cook. According to Lisa's mom, Tawny Williams, Chelsea had become obsessed with Lisa, targeting her online and harassing her in person, The Associated Press reported.

“I worried for her safety every day,” Tawny said.

Travis and Lisa met at a bank where they both worked outside Salt Lake City, Utah, and began dating earlier this year, according to the AP. Chelsea, a yoga teacher at a high school, seemed to struggle with the relationship, though things had appeared fine in the days leading up to the shooting, Lisa's family said. 

On that Sunday after Thanksgiving, Chelsea went to her former husband's apartment in Midvale, Utah, to bring cold medicine for one of their 3-year-old twins, according to police. Her ex was in the parking lot when Chelsea showed up and immediately demanded that she leave.

Instead, Chelsea allegedly locked herself in the apartment's bathroom and refused to leave, authorities said. When she later emerged, she appeared to go to put on her coat, but actually reached into the pocket and pulled out a gun, firing at Lisa. The twins were there to witness the shooting.

According to police, Travis had to pin his wife to a wall while he waited for officers to arrive. 

Chelsea is charged with aggravated murder. Her next hearing is set for January. She also already faced separate charges of domestic violence stemming from a different incident, and has pleaded not guilty in that case.