There is something that is called a Lampron-Dwyer Protocol you have to file and do a service of a motion. It is under the Mass Rules of Criminal Procedure 17.  The idea is if there is a 3^rd party record that you are seeking, there are some requirements that need to occur which you can find from the case law and from some of the rules of procedure.

There are different details including that the person seeking those records has to serve a Motion Affidavit on the parties; including the record holder along with notifying them of the date and place of the hearing and giving the 3^rd party the opportunity to address the court.  If there are any statutory privileges applicable to the records sought shall remain in effect unless and until the third-party subject affirmatively waives any such privilege, and that failure to attend the hearing shall not constitute a waiver of any such privilege; and if the third-party subject is the victim in the case, he or she has the opportunity to confer with the prosecutor prior to the hearing.

The party looking for those documents has to show good cause by showing that the documents are evidentiary and relevant; that they are not otherwise procurable reasonably in advance of trial by exercise of due diligence;  that the party cannot properly prepare for trial without such production and inspection in advance of trial, and that the failure to obtain such inspection may tend to unreasonably delay the trial;  that the application is made in good faith and is not intended as a general fishing expedition.  There are more technicalities to it and requirements, but its idea is that if there are a certain 3^rd party records in a criminal case, there are very strict requirements about what needs to occur.