So you think this relative became invisible, entered the house with a key, walked past Sergio who was sleeping on the couch on the wall outside Isabel's room. He knew to not enter her brothers' room where she normally slept. He knew he should enter her room. He killed Isabel (articles state FBI dog "hit" on something) and then let her dead body lie in the house for 15+ minutes (amount of time it takes for cadaverine to develop for FBI cadaver dog to smell cadaverine and be able to "hit" on some object). He opened up Isabel's window and took off the screen to make it appear that he kidnapped Isabel's dead body from her window,but he really didn't. (Surveillance video from a home security store didn't show anyone climbing out Isabel's window.) Then he carried Isabel's dead body out the front door, Becky's bedroom window, the tiny bathroom window, the sliding glass door, the guest bedroom window, or the boys' windows. He and Isabel's dead body became invisible (if you think he used the front door or front gate), put her dead body into a car, and drove it to a remote location near Tucson. (Office Max's surveillance camera pointed up 12th Street.)
Imo, Isabel's dead body was wrapped in an impermeable object, taken from her room, and loaded into a car located in the Celis' garage. The relative wouldn't have keys to Becky's or Sergio's cars located in the garage. He had his own vehicle.
