A Kentucky woman found dead with her two children in January killed them and then herself, a sheriff said.

The Boone County Sheriff’s Office said in a statement on Tuesday that detectives had concluded their investigation into the deaths.

Deputies responded on Jan. 9 to an apartment in Walton and found two adults and two children with multiple stab wounds. The woman, Monique S. Pena, 31, and children, 12-year-old Nikki Romero Pena and 3-year-old Katie Farrell-Pena, were pronounced dead at the scene. The man, Matthew Farrell, 36, was taken to a hospital with serious injuries.

Farrell told deputies he was asleep when Pena began stabbing him and he fled the apartment believing he was the sole target of the attack.

The crime scene and other evidence collected by investigators, including statements from Pena’s family, corroborated his explanation, the sheriff said. Pena’s family told investigators that she was experiencing unusual and extreme paranoia in the days before the attack.

Based on the evidence and statements, detectives concluded the deaths were a murder-suicide, the sheriff said.