Dateline | January 11, 2013
>>> what you're watching is far better than any eyewitness. what you're seeing is the exact record of the moment in time. this is giselle esteban at michelle le's nursing school the day before michelle vanished. why she was here was a mystery, but what she did, that, inspector richey pieced together from giselle 's electronic trail which picked her up at the morning in the nursing school posing as a prospective student. while there she stole an instructor's key card and then appeared to test whether it would work by entering this break room.
>> and then at 5:30 in the evening when the campus is closed she gains access through the back door using that electronic key card .
>> same card.
>> throughout the campus they're in the classrooms and the hallways there's cameras and it shows giselle walking around with a lab coat on. her glasses up and she's going around turning on computers.
>> giselle can also be seen with a class roster stolen from an instructor's office.
>> you can see a class roster because it has all of the students and photographs on there so it's not just typed. it's photographs so you can see that there is a class roster and she's walking around as if she's pretending to be an instructor or something like that. she's there for an hour and a half or so and then she leaves.
>> all of this the night before michelle le disappeared. what was jish giselle doing? on the morning after giselle disappeared giselle esteban went with her daughter in tow to an apple store and there she was on the security camera . that's her there in the top left of her screen having one of the employees unlock an iphone . she told the apple employee that her daughter had put a code into the phone and locked it. once he unlocked it the phone started pinging and ringing.
>> and just at that very moment, as cell phone records showed, michelle le's iphone began pinging on the cell phone tower not far from the apple store . now it was a matter of following the signal which led to this chuck e. cheese restaurant a few miles away where the phone turned up again.
>> giselle was seen on a video showing a white iphone . remember, this was the day after michel michelle 's disappearance when her family were frantically calling and texting her. it looks like jgiselle is sending out text messages and at that moment, giselle 's iphone was pinging off a nearby cell tower . to richey , it seemed quite clear, giselle esteban was the one using michelle 's phones to send those creepy text messages to worried friends and family and to him, and giselle did all this while on a shopping trip with her daughter.
>> and she's on that phone, roughly the same time that she's getting text messages from the classmates and family members and things like that, and then i sent her a second text message at roughly at 3:15 in the afternoon saying this is not a joke. this is the police department . you need to contact me right now. that was the last contact. that's when her phone went off.
>> the evidence was mounting so richey stepped up his surveillance on giselle . we placed a tracker on her car.
>> to see if she would take us to a location that michelle would possibly be.
>> well, that didn't happen. not to say, though, her behavior wasn't suspicious. remember the vigil the le family held the week after the disappearance, the one attended by giselle 's boyfriend scott , it turned out giselle was there, too, sort of. the tracking device showed giselle circling the block as giselle 's family pleaded for help and later it showed her driving past scott 's house. why? richey was all, but sure now giselle had something to do with michelle 's disappearance. the question now was did she have some help?
>> there was something that we had to look at.
>> if so, who?
>> yeah. dive into her life. who's her friends and who can we talk to that knows giselle ?
>> richey consulted an alameda county assistant d.a., a guy named butch. butch ford.
>> some of my colleagues their response was who helped her do it because she's a woman. she's pregnant. in order to do this she had to have help.
>> prosecutors had a hard time believing esteban was physically capable of killing michelle le all by herself.
>> we encouraged them to make sure they eliminated any possible suspects such as the father of giselle 's child.
>> that would be scott , the ex-boyfriend butch is referring to. and so everybody's antenna went up in late july, 63 days after michelle 's disappearance as the family searched the hills for her. detective richey got a very strange phone call from scott who sounded out of breath.
>> saying that he believed that he had found michelle 's phone. i asked him, where did you find michelle 's phone?
>> in the backseat of his car.
>> coming up, at first, police doubt scott 's story? have we missed something? is he the other part of this.
>> you deserve to die for your lies.
>> when "vanished" continues.