The Middlesex County Probation Department is located in New Brunswick and Perth Amboy. The telephone number for the New Brunswick office is 732-981-3250.Find legal resources, and get help with understanding court forms and procedures. Announcements. View the latest news and announcements. Pre-arrest investigations in Middlesex County, NJ: essential legal insights and guidance for protecting your rights. The Criminal Division is responsible for processing and managing all indictable criminal cases involving adult offenders. If you believe you are eligible for a Public Defender, you must fill out the required forms. Understanding the criminal case process in Middlesex County NJ. If you have questions contact our law office today for a free consultation. Please complete the following questionnaire in entirety. After filling out the form, they can be submitted via online submission, E-Mail, Fax, USPS or hand deliver the document to the facility directly.