It was pre-meditated murder. She had been planning this for several months. The alleged fight the previous night probably triggered the actual murder. I had read previously that Casey knew that Cindy could not baby-sit Caylee on the 16th. Why would she expect Cindy to baby-sit after a big fight and knowing full well that Cindy had to work late? KC continued to make calls to Cindy even after 6:30 p.m. I also remember reading somewhere that KC didn't ask AH to baby-sit Caylee that day. She could have called a number of friends and atleast tried to get them to baby-sit Caylee. She did not.
I still think KC murdered Caylee shortly after her morbid search on the computer in the comfort of her home. If KC left hopespring drive that day expecting someone to baby-sit Caylee then she would have put on a pair of shoes for Caylee and packed an overnight bag as well. She was SURE that Caylee wouldn't need any of that. She may have been driving around looking for a place to dump Caylee after that while there was no phone activity.
BBM-KC was prepared to drop Caylee off at Gentiva, I am sure...
Keep in mind, the times that we have personally seen Casey's rage are often the times when Cindy just won't cooperate with her...
We heard Casey lose it (as much as she could while standing in front of guards) with Cindy on the phone call from jail-she stops short of giving the same attitude to Lee and Christina, her "friends," but feels very free to abuse her mother.
Then, Casey's meltdown with Cindy during the jail visit. She certainly does not react to George in the same was she does Cindy, at least in my perception.
Then, Annie's commentary about the way Casey yelled at Cindy.
And the accounts from her jailmates about KC's anger towards Cindy; the faux fit she threw when Cindy cremated Caylee's remains, etc.
It's not so much that Cindy is the only one Casey is capable of being angry at, it's that Cindy is the one that KC feels most comfortable aggressively abusing.
And punishing.
Casey's rage is there with or without Cindy in her life. Cindy just exacerbated the situation by her mere existence. Cindy was always (perceived by Casey as) the annoying little Jimeney Cricket character there to chirp in when Casey wanted ultimate independence. Why couldn't Cindy just shut up and watch Caylee while KC had some fun time in the sack with Tony? It was not until Det. Wells suggested Casey should feel guilt about her treatment of Cindy (my paraphrase) that it dawned on the sociopath to pretend she felt any guilt at all.
Remember, Casey's tantrums past had effected Cindy to the degree that she refused to discipline Casey for the fake $4,000 deposit and the Sports Authority lie. Cindy equalled doormat...but one of those stubborn doormats that gets debris stuck in it, so you really have to give it a swift hit with a broom or foot to make it an acceptable doormat again. Oh my, I digress...
OF COURSE she thought Cindy would suck up the fight of the 15th and watch Caylee as usual.
Cindy must have been holding debris, er, ground, and George was backing her up. Which could play into why George called the house shortly after leaving on June 16th.
Cindy's responses to KC between the 15th and the 16th lead to a rageful outburst that was the catalyst to bring premeditation to fruition.