Since he served 20 years for the last kidnapping he committed that left a living victim, I think it's not a leap to assume he didn't intend on leaving a living victim to testify as he did in his previous abduction. I am sure there is evidence to support the premeditation. Besides, it only takes seconds to premeditate. There doesn't need to be a diagram or written plan per se. Seconds is enough time to conclude I now intend to make sure this victim is not alive to testify. I suspect he knew when he grabbed her he would be killing her rather than letting her live to tell so to speak.