Speaking to iVillage as part of the promotion for her new movie "Killers", Katherine explained that the main motivation for her recent departure from "Grey's Anatomy" was that it afforded her the opportunity to spend more time with her baby daughter Naleigh.

"I really wanted to see it through," she said of the ABC medical drama, "But I'll forever be grateful, no matter how hard that decision was, that I made it because I've had this unbelievable time with my daughter."

Check out the video interview to hear Katie talk about her daughter, their relationship and what surprised her most about "Killers" co-star Ashton Kutcher.

Kutcher himself recently told MTV that Katherine was "an unbelievable actress, a dream," he gushed. "She has this childlike quality that is so valuable when you're working in a profession where you have to use your imagination."