Hello. My name is***** am a Florida licensed attorney and I will be happy to answer your question.
I am sorry to hear about this unfortunate situation.
Unfortunately, if the phone was lost and found by the school staff and the phone received text messages related to criminal drug activity, then the school has legal right and duty to report such criminal issue to the police and police can in fact open criminal investigation and secure any evidence of criminal activity, such as a cell phone, until a search warrant is obtained to unlock the phone.
It is important to consult and retain an experienced local criminal defense attorney to represent your son in this matter and to have this local attorney handle any and all communication with police or anyone else about the case.
You can find an experienced and skilled local criminal law attorney by using this established and reputable attorney information / referral websites:
When, choosing a local attorney to represent you, it would be a good idea to choose someone who has a practice exclusively dedicated to criminal law, has at least 10 years of experience and handled similar matters and also regularly practices before the court located in the jurisdiction where your matter will be heard.
I wish you the best of luck!