Ideally you will need a Bachelors. There is not a lot of value in getting a second Associates degree in anything. That just gets you two degrees that no medium to large employer will value. The only exception on this may be a law enforcement job situation. They might value the Associates because they will want to train you anyway. Mainly in the private job sector an Associates degree has only one benefit - it is a cheaper way to do year 1&2 of a Bachelors degree.
The college degree path that you would pursue would usually be Computer Science or Computer Information Systems. However, more colleges may begin offering concentrations specific to this line of work. Often you would do some certifications to work in this area. There are more general computing Security Certs like Security+ and CISSP and then more specialized ones like the CEH (Certified Ethical Hacker). If you wanted to work in an agency setting you would likely have some Police Science course involved.
Some Computer Forensics specialists are former policeman who have retired out or switched careers to the private sector. In the area of Computer Forensics there are a significant number of certifications and licenses that are needed. These are the credentials that would allow you to testify in a court as an expert witness.
Also, there is a dark side to working in Computer Forensics. If you are working in a law enforcement situation, you will be dealing with cases that are extremely disturbing and information that you are required to view and analyze and then testify about could be disturbing also. Child Pornography, murder, kidnappings are all areas you could be immersed in at times. On TV these types of jobs are sanitized. In real life they are much different.
I have given you some links to some private companies. If you browse through these websites you will find all the certs and licenses required to work in this field.
EnCE EnCase Certified Examiner
Certified Forensic Computer Examiner
IACIS Certified Electronic Evidence Collection Specialist
IACIS Advanced Seizure and Processing of DOS & Windows OS Certificate
IACIS Advanced Forensic Network Essentials Certificate
IACIS Advanced Unix Training Certificate
HTCN Advanced Certification, Computer Crime Investigator
HTCN Advanced Certification, Computer Forensic Technician
ACFS Certified Fraud Specialist
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