I think old Javier left some important details out of his story he used to explain how Valerie died or should I say how he killed her.
I would think there would have to be some form of communication between Valerie and Javier prior to him coming to her apartment, which could be confirmed through phone or text records. Would seem strange if there was no communication between the two, which would point to Javier showing up unannounced and uninvited.
Regardless if Javier came to Valerie's apartment invited or unannounced, I think Javier likely became violent with her, raped her and then killed her. He may have bound her hands and feet and placed a gag over her mouth as a way to control her and to keep others from hearing her scream for help. For Javier to bind Valerie's feet and knees, tie her hands behinds her back and places tape over her mouth after she was dead makes absolutely no sense at all. And if she was still alive, why would he do such things if the two of them were having consensual sex?
Then throw in the fact that Valerie feared she would be murdered and it's easy for me to see he likely wasn't invited over for dinner.
JMO