I cannot practice law in AZ but I can locate information for you.
According to http://en.wikipedia.org/wiki/Miranda_warning
Miranda warning is a warning given by police to criminal suspects in police custody, or in a custodial situation, before they are asked questions relating to the commission of a crime. A custodial situation is where the suspect's freedom of movement is restrained although he or she is not under arrest. An incriminating statement by a suspect will not constitute admissible evidence unless the suspect was advised of his or her "Miranda rights
" and made a knowing, intelligent, and voluntary waiver of those rights. However, police may request biographical information such as name, date of birth, and address, without first reading suspects their Miranda warnings
You can read the Miranda case, MIRANDA V. ARIZONA, 384 U. S. 436 (1966) at http://supreme.justia.com/us/384/436/case.html
at page 39 has a list of the police agencies in MO that do record interrogations. Even if the agency who arrested her is not on that list they still might have recorded it. Her lawyer will find out once she has a lawyer.
There does not seem to be any requirement that custodial interrogations be recorded, but it seems the more professional police agencies routinely record them, and for obvious reasons. If she is alleging the cops coerced her confession by heavy handed interrogation methods continued after she demanded counsel and they do not have tapes to prove otherwise, she may very well convince a Court
to suppress the confession.
Again I urge you to call a few of the local attorneys on the list I linked in my last post and find someone she is comfortable with to discuss her case. If she cannot afford an attorney she should call the public defender.
Here is an application for the services of the PD: http://www.publicdefender.mo.gov/clients/Application_for_PD_Services.pdf
is a map so you can determine which district she is in to help find your local office.