In order to solve the case, can the police check the phone and text messages of the deceased before his death?

Yes, according to official website, the police can only retrieve the call records according to the mobile phone number, and there is no way to know the call content, unless the public security organs go through strict examination and approval procedures and take technical policy measures for the deceased in advance to obtain the mobile phone call content of the relevant business hall. For specific information, please pay attention to official website for first-hand authoritative information.