The duct tape is not likely to have been used to reduce leakage or stage a kidnapping. First, if it was to reduce leakage, there would have been more tape around the eyes, nose, pelvic and anal area. There has been no indication more tape was present than around the skull in the area of the mouth. Second, there was no kidnapping story even hinted at by KC until she had a talk with LA on the evening of July 15. Then, that story grew with additional details as earlier details were disproved. Therefore, at the time of disposal of the body, KC had not yet fabricated the kidnapping story.
So, what is the probable explanation? The computer shows there was research into chloroform, making chloroform and neck breaking prior to the big Scamthony blow-out on June 15, 2008 over financial issues, child care issues, unfit mother issues, custody issues and independent living issues. Then the blow-out. KC left in a rage. There was duct tape and a knife found in the car. Friends also said when KC previously brought Caylee to parties, Caylee would "sleep" through any amount of noise or commotion around her. She may have been chloroformed. Chloroform is a short acting agent. A constant drip is needed to keep a person unconscious during a 1 or 2 hour surgery. A wire mesh mask covered with absorbant cotton is used to keep the damp chloroform away from the mouth and nose because it causes skin irritation and redness. Some prior photos of Caylee show redness around the mouth area. It also has nasty side effects. A person becoming conscious after being chloroformed will have nausea, vomiting and severe headaches. IF KC left the house in a rage on June 15, 2008, and headed to TonE's house, but took Caylee with her because of the unfit mother, child care/responsibility and impending custody challenge by CA; and some prior boyfriend had indicated it wasn't good to have Caylee present at a sleep-over with sexual activity, then the only place KC had for Caylee was the car, or the motel where she was seen pacing. KC wanted Caylee unconscious for a longer period of time than ever before. The trunk was saturated with a substantial amount of chloroform. The duct tape and knife were in the car. KC didn't want Caylee to be heard crying out or to vomit. There is a distince possibility that KC chloroformed Caylee, slapped the duct tape around her head and mouth tight enough to preserve soft tissue underneath (unwittingly), and left her in the trunk. KC's emotions about all the attention of her parents being "all about Caylee" underscores this willingness to hurt Caylee or extreme disregard and gross negligence in her care. Caylee died, perhaps of an overdose of chloroform, or by asphixiating on her own vomit (drowning in her own vomit), which can happen to a semi-conscious patient regaining conscious. That is why medical people watch them in post-op and keep the airway clear. In this event, not only did this action meet the legal definitions of premeditation and first degree homicide, it was no accidental overdose because administering chloroform in the first instance to achieve unconsciousness of a toddler rather than provide the legal duty of parental care is by itself extreme negligence and physical child abuse.
In light of the above, I am also thinking this probably meets the legal definition of torture, depending on Florida caselaw. The chloroform and duct tape uses were torture.