I was fired, my employer will not give me a finished copy of projects I completed on the job, can they do this

This question is more for labor law than intellectual property as the crux of the issue is the rights of the employee/employer. Employment contracts typically govern this type of situation and are commonly used for science and engineering. You do have a right to ask the HR person for a copy of your employment contract(s). You will want to show the contract(s) to an attorney versed in Colorado employment law. More broadly, without an employment agreement, the law does have 'default' settings for these situations. Inventors are said to own patent rights absent a signed agreement to assign those rights. All other IP created on the job is typically owned by the employer. Many of the rules in this area fall under 'work-for-hire' provisions. Relative to the work you brought with you, you would need to be able to prove that you brought it with you in order to reclaim it from your employer's possession. Good luck, Todd